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changeset 1392:080862694980

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Merge pull request #33 from bengardner/termcodes termcodes: make VEOL2, VWERASE, VLNEXT, ECHOCTL, and ECHOKE optional
author Matt Johnston <matt@ucc.asn.au>
date Fri, 02 Jun 2017 23:01:54 +0800
parents b413787adcdb (diff) 8aed91ebf3c7 (current diff)
children f386d2e9dc75
files
diffstat 33 files changed, 345 insertions(+), 210 deletions(-) [+]
line wrap: on
line diff
--- a/.hgsigs	Wed May 25 10:03:53 2016 -0500
+++ b/.hgsigs	Fri Jun 02 23:01:54 2017 +0800
@@ -21,3 +21,5 @@
 926e7275cef4f4f2a4251597ee4814748394824c 0 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
 fd1981f41c626a969f07b4823848deaefef3c8aa 0 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
 70705edee9dd29cd3d410f19fbd15cc3489313e2 0 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
+9030ffdbe5625e35ed7189ab84a41dfc8d413e9c 0 iQIcBAABCgAGBQJXkOg0AAoJEESTFJTynGdzc1kP/3vSKCnhOOvjCjnpTQadYcCUq8vTNnfLHYVu0R4ItPa/jT6RmxoaYP+lZnLnnBx9+aX7kzwHsa9BUX3MbMEyLrOzX2I+bDJbNPhQyupyCuPYlf5Q9KVcO9YlpbsC4q5XBzCn3j2+pT8kSfi9uD8fgY3TgE4w9meINrfQAealfjwMLT8S/I49/ni0r+usSfk/dnSShJYDUO7Ja0VWbJea/GkkZTu30bCnMUZPjRApipU3hPP63WFjkSMT1rp2mAXbWqyr9lf8z32yxzM9nMSjq4ViRFzFlkGtE3EVRJ4PwkO7JuiWAMPJpiQcEr+r52cCsmWhiGyHuINo01MwoMO9/n6uL1WVa3mJcE9se3xBOvfgDu2FRFGCAdm1tef+AGVo9EG1uJXi0sX2yUc6DMeuYaRWrXMMlZh7zp9cuNU9Y/lLui9RFmq66yeXG3Z2B72doju3Ig5QGrNNw2AOsSzeHdAtOp6ychqPcl9QfIeJQG18KyPSefZKM3G8YRKBRIwXFEH6iZJe5ZIP4iXrHDMn2JqtTRtDqKR8VNDAgb9z4Ffx8QRxFyj5JzTTMM1GddHb9udLvTQlO0ULYG7hCSMRNzvUBE2aTw8frjLRyfyyg3QpDu/hz8op8s1ecE8rTCD8RuX9DiiylNozypPtGNS+UDbAmkc1PCWaRpPVl+9K6787
+5c9207ceedaea794f958224c19214d66af6e2d56 0 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
--- a/.hgtags	Wed May 25 10:03:53 2016 -0500
+++ b/.hgtags	Fri Jun 02 23:01:54 2017 +0800
@@ -53,3 +53,5 @@
 9a944a243f08be6b22d32f166a0690eb4872462b DROPBEAR_2015.71
 78b12b6549be08b0bea3da329b2578060a76ca31 DROPBEAR_2016.72
 309e1c4a87682b6ca7d80b8555a1db416c3cb7ac DROPBEAR_2016.73
+0ed3d2bbf956cb8a9bf0f4b5a86b7dd9688205cb DROPBEAR_2016.74
+c31276613181c5cff7854e7ef586ace03424e55e DROPBEAR_2017.75
--- a/CHANGES	Wed May 25 10:03:53 2016 -0500
+++ b/CHANGES	Fri Jun 02 23:01:54 2017 +0800
@@ -1,3 +1,70 @@
+2017.75 - 18 May 2017
+
+- Security: Fix double-free in server TCP listener cleanup
+  A double-free in the server could be triggered by an authenticated user if
+  dropbear is running with -a (Allow connections to forwarded ports from any host)
+  This could potentially allow arbitrary code execution as root by an authenticated user.
+  Affects versions 2013.56 to 2016.74. Thanks to Mark Shepard for reporting the crash.
+  CVE-2017-9078 https://secure.ucc.asn.au/hg/dropbear/rev/c8114a48837c
+
+- Security: Fix information disclosure with ~/.ssh/authorized_keys symlink.
+  Dropbear parsed authorized_keys as root, even if it were a symlink. The fix
+  is to switch to user permissions when opening authorized_keys
+
+  A user could symlink their ~/.ssh/authorized_keys to a root-owned file they
+  couldn't normally read. If they managed to get that file to contain valid
+  authorized_keys with command= options it might be possible to read other
+  contents of that file.
+  This information disclosure is to an already authenticated user.
+  Thanks to Jann Horn of Google Project Zero for reporting this.
+  CVE-2017-9079 https://secure.ucc.asn.au/hg/dropbear/rev/0d889b068123
+
+- Generate hostkeys with dropbearkey atomically and flush to disk with fsync
+  Thanks to Andrei Gherzan for a patch
+
+- Fix out of tree builds with bundled libtom
+  Thanks to Henrik Nordström and Peter Krefting for patches.
+
+2016.74 - 21 July 2016
+
+- Security: Message printout was vulnerable to format string injection.
+
+  If specific usernames including "%" symbols can be created on a system
+  (validated by getpwnam()) then an attacker could run arbitrary code as root
+  when connecting to Dropbear server.
+
+  A dbclient user who can control username or host arguments could potentially
+  run arbitrary code as the dbclient user. This could be a problem if scripts
+  or webpages pass untrusted input to the dbclient program.
+  CVE-2016-7406
+  https://secure.ucc.asn.au/hg/dropbear/rev/b66a483f3dcb
+
+- Security: dropbearconvert import of OpenSSH keys could run arbitrary code as
+  the local dropbearconvert user when parsing malicious key files
+  CVE-2016-7407
+  https://secure.ucc.asn.au/hg/dropbear/rev/34e6127ef02e
+
+- Security: dbclient could run arbitrary code as the local dbclient user if
+  particular -m or -c arguments are provided. This could be an issue where
+  dbclient is used in scripts.
+  CVE-2016-7408
+  https://secure.ucc.asn.au/hg/dropbear/rev/eed9376a4ad6
+
+- Security: dbclient or dropbear server could expose process memory to the
+  running user if compiled with DEBUG_TRACE and running with -v
+  CVE-2016-7409
+  https://secure.ucc.asn.au/hg/dropbear/rev/6a14b1f6dc04
+
+  The security issues were reported by an anonymous researcher working with
+  Beyond Security's SecuriTeam Secure Disclosure www.beyondsecurity.com/ssd.html
+
+- Fix port forwarding failure when connecting to domains that have both
+  IPv4 and IPv6 addresses. The bug was introduced in 2015.68
+
+- Fix 100% CPU use while waiting for rekey to complete. Thanks to Zhang Hui P
+  for the patch
+
+
 2016.73 - 18 March 2016
 
 - Support syslog in dbclient, option -o usesyslog=yes. Patch from Konstantin Tokarev
@@ -32,6 +99,7 @@
 
 - Validate X11 forwarding input. Could allow bypass of authorized_keys command= restrictions,
   found by github.com/tintinweb. Thanks for Damien Miller for a patch. CVE-2016-3116
+  https://secure.ucc.asn.au/hg/dropbear/rev/a3e8389e01ff
 
 2015.71 - 3 December 2015
 
@@ -310,9 +378,11 @@
 - Limit the size of decompressed payloads, avoids memory exhaustion denial
   of service 
   Thanks to Logan Lamb for reporting and investigating it. CVE-2013-4421
+  https://secure.ucc.asn.au/hg/dropbear/rev/0bf76f54de6f
 
 - Avoid disclosing existence of valid users through inconsistent delays
   Thanks to Logan Lamb for reporting. CVE-2013-4434
+  https://secure.ucc.asn.au/hg/dropbear/rev/d7784616409a
 
 - Update config.guess and config.sub for newer architectures
 
@@ -415,6 +485,7 @@
   This bug affects releases 0.52 onwards. Ref CVE-2012-0920.
   Thanks to Danny Fullerton of Mantor Organization for reporting
   the bug.
+  https://secure.ucc.asn.au/hg/dropbear/rev/818108bf7749
 
 - Compile fix, only apply IPV6 socket options if they are available in headers
   Thanks to Gustavo Zacarias for the patch
--- a/atomicio.c	Wed May 25 10:03:53 2016 -0500
+++ b/atomicio.c	Fri Jun 02 23:01:54 2017 +0800
@@ -1,6 +1,8 @@
+/* $OpenBSD: atomicio.c,v 1.17 2006/04/01 05:51:34 djm Exp $ */
 /*
- * Copied from OpenSSH 3.6.1p2.
+ * Copied from OpenSSH/OpenBSD.
  * 
+ * Copyright (c) 2005 Anil Madhavapeddy. All rights reserved.
  * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
  * All rights reserved.
  *
@@ -25,39 +27,32 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-/* RCSID("OpenBSD: atomicio.c,v 1.10 2001/05/08 22:48:07 markus Exp "); */
+#include "includes.h"
 
 #include "atomicio.h"
 
 /*
- * ensure all of data on socket comes through. f==read || f==write
+ * ensure all of data on socket comes through. f==read || f==vwrite
  */
-ssize_t
-atomicio(f, fd, _s, n)
-	ssize_t (*f) ();
-	int fd;
-	void *_s;
-	size_t n;
+size_t
+atomicio(ssize_t (*f) (int, void *, size_t), int fd, void *_s, size_t n)
 {
 	char *s = _s;
+	size_t pos = 0;
 	ssize_t res;
-	size_t pos = 0;
 
 	while (n > pos) {
 		res = (f) (fd, s + pos, n - pos);
 		switch (res) {
 		case -1:
-#ifdef EWOULDBLOCK
-			if (errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK)
-#else
 			if (errno == EINTR || errno == EAGAIN)
-#endif
 				continue;
-			/* FALLTHROUGH */
+			return 0;
 		case 0:
-			return (res);
+			errno = EPIPE;
+			return pos;
 		default:
-			pos += res;
+			pos += (size_t)res;
 		}
 	}
 	return (pos);
--- a/atomicio.h	Wed May 25 10:03:53 2016 -0500
+++ b/atomicio.h	Fri Jun 02 23:01:54 2017 +0800
@@ -1,8 +1,7 @@
+/* $OpenBSD: atomicio.h,v 1.7 2006/03/25 22:22:42 djm Exp $ */
 
 /*
- * Copied from OpenSSH 3.6.1p2, required for loginrec.c
- *
- * $OpenBSD: atomicio.h,v 1.4 2001/06/26 06:32:46 itojun Exp $
+ * Copied from OpenSSH/OpenBSD, required for loginrec.c
  *
  * Copyright (c) 1995,1999 Theo de Raadt.  All rights reserved.
  * All rights reserved.
@@ -28,9 +27,9 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include "includes.h"
+/*
+ * Ensure all of data on socket comes through. f==read || f==vwrite
+ */
+size_t	atomicio(ssize_t (*)(int, void *, size_t), int, void *, size_t);
 
-/*
- * Ensure all of data on socket comes through. f==read || f==write
- */
-ssize_t	atomicio(ssize_t (*)(), int, void *, size_t);
+#define vwrite (ssize_t (*)(int, void *, size_t))write
--- a/buffer.c	Wed May 25 10:03:53 2016 -0500
+++ b/buffer.c	Fri Jun 02 23:01:54 2017 +0800
@@ -109,6 +109,7 @@
 		dropbear_exit("Bad buf_setlen");
 	}
 	buf->len = len;
+	buf->pos = MIN(buf->pos, buf->len);
 }
 
 /* Increment the length of the buffer */
@@ -141,9 +142,10 @@
 /* increment the position by incr, negative values are allowed, to
  * decrement the pos*/
 void buf_incrpos(buffer* buf,  int incr) {
-	if (incr > BUF_MAX_INCR ||
-			(unsigned int)((int)buf->pos + incr) > buf->len 
-			|| ((int)buf->pos + incr) < 0) {
+	if (incr > BUF_MAX_INCR 
+		|| incr < -BUF_MAX_INCR 
+		|| (unsigned int)((int)buf->pos + incr) > buf->len
+		|| ((int)buf->pos + incr) < 0) {
 		dropbear_exit("Bad buf_incrpos");
 	}
 	buf->pos += incr;
@@ -184,7 +186,7 @@
  * the next len bytes from that position can be used */
 unsigned char* buf_getptr(buffer* buf, unsigned int len) {
 
-	if (buf->pos + len > buf->len) {
+	if (len > BUF_MAX_INCR || buf->pos + len > buf->len) {
 		dropbear_exit("Bad buf_getptr");
 	}
 	return &buf->data[buf->pos];
@@ -194,7 +196,7 @@
  * This allows writing past the used length, but not past the size */
 unsigned char* buf_getwriteptr(buffer* buf, unsigned int len) {
 
-	if (buf->pos + len > buf->size) {
+	if (len > BUF_MAX_INCR || buf->pos + len > buf->size) {
 		dropbear_exit("Bad buf_getwriteptr");
 	}
 	return &buf->data[buf->pos];
--- a/cli-agentfwd.c	Wed May 25 10:03:53 2016 -0500
+++ b/cli-agentfwd.c	Fri Jun 02 23:01:54 2017 +0800
@@ -130,7 +130,7 @@
 	}
 	buf_setpos(payload, 0);
 
-	ret = atomicio(write, fd, buf_getptr(payload, payload->len), payload->len);
+	ret = atomicio(vwrite, fd, buf_getptr(payload, payload->len), payload->len);
 	if ((size_t)ret != payload->len) {
 		TRACE(("write failed fd %d for agent_request, %s", fd, strerror(errno)))
 		goto out;
--- a/cli-main.c	Wed May 25 10:03:53 2016 -0500
+++ b/cli-main.c	Fri Jun 02 23:01:54 2017 +0800
@@ -98,29 +98,30 @@
 #endif /* DBMULTI stuff */
 
 static void cli_dropbear_exit(int exitcode, const char* format, va_list param) {
+	char exitmsg[150];
+	char fullmsg[300];
 
-	char fmtbuf[300];
-	char exitmsg[500];
+	/* Note that exit message must be rendered before session cleanup */
 
+	/* Render the formatted exit message */
+	vsnprintf(exitmsg, sizeof(exitmsg), format, param);
+
+	/* Add the prefix depending on session/auth state */
 	if (!sessinitdone) {
-		snprintf(fmtbuf, sizeof(fmtbuf), "Exited: %s",
-				format);
+		snprintf(fullmsg, sizeof(fullmsg), "Exited: %s", exitmsg);
 	} else {
-		snprintf(fmtbuf, sizeof(fmtbuf), 
+		snprintf(fullmsg, sizeof(fullmsg), 
 				"Connection to %s@%s:%s exited: %s", 
 				cli_opts.username, cli_opts.remotehost, 
-				cli_opts.remoteport, format);
+				cli_opts.remoteport, exitmsg);
 	}
 
-	/* Arguments to the exit printout may be unsafe to use after session_cleanup() */
-	vsnprintf(exitmsg, sizeof(exitmsg), fmtbuf, param);
-
 	/* Do the cleanup first, since then the terminal will be reset */
 	session_cleanup();
 	/* Avoid printing onwards from terminal cruft */
 	fprintf(stderr, "\n");
 
-	dropbear_log(LOG_INFO, "%s", exitmsg);;
+	dropbear_log(LOG_INFO, "%s", fullmsg);
 	exit(exitcode);
 }
 
--- a/cli-session.c	Wed May 25 10:03:53 2016 -0500
+++ b/cli-session.c	Fri Jun 02 23:01:54 2017 +0800
@@ -287,7 +287,7 @@
 				int devnull;
 				/* keeping stdin open steals input from the terminal and
 				   is confusing, though stdout/stderr could be useful. */
-				devnull = open(_PATH_DEVNULL, O_RDONLY);
+				devnull = open(DROPBEAR_PATH_DEVNULL, O_RDONLY);
 				if (devnull < 0) {
 					dropbear_exit("Opening /dev/null: %d %s",
 							errno, strerror(errno));
--- a/cli-tcpfwd.c	Wed May 25 10:03:53 2016 -0500
+++ b/cli-tcpfwd.c	Fri Jun 02 23:01:54 2017 +0800
@@ -234,7 +234,7 @@
 	char *origaddr = NULL;
 	unsigned int origport;
 	m_list_elem * iter = NULL;
-	struct TCPFwdEntry *fwd;
+	struct TCPFwdEntry *fwd = NULL;
 	char portstring[NI_MAXSERV];
 	int err = SSH_OPEN_ADMINISTRATIVELY_PROHIBITED;
 
@@ -265,7 +265,7 @@
 	}
 
 
-	if (iter == NULL) {
+	if (iter == NULL || fwd == NULL) {
 		/* We didn't request forwarding on that port */
 		cleantext(origaddr);
 		dropbear_log(LOG_INFO, "Server sent unrequested forward from \"%s:%d\"", 
--- a/common-algo.c	Wed May 25 10:03:53 2016 -0500
+++ b/common-algo.c	Fri Jun 02 23:01:54 2017 +0800
@@ -529,21 +529,6 @@
 	return NULL;
 }
 
-static void
-try_add_algo(const char *algo_name, algo_type *algos, 
-		const char *algo_desc, algo_type * new_algos, int *num_ret)
-{
-	algo_type *match_algo = check_algo(algo_name, algos);
-	if (!match_algo)
-	{
-		dropbear_log(LOG_WARNING, "This Dropbear program does not support '%s' %s algorithm", algo_name, algo_desc);
-		return;
-	}
-
-	new_algos[*num_ret] = *match_algo;
-	(*num_ret)++;
-}
-
 /* Checks a user provided comma-separated algorithm list for available
  * options. Any that are not acceptable are removed in-place. Returns the
  * number of valid algorithms. */
@@ -551,30 +536,43 @@
 check_user_algos(const char* user_algo_list, algo_type * algos, 
 		const char *algo_desc)
 {
-	algo_type new_algos[MAX_PROPOSED_ALGO];
-	/* this has two passes. first we sweep through the given list of
-	 * algorithms and mark them as usable=2 in the algo_type[] array... */
-	int num_ret = 0;
+	algo_type new_algos[MAX_PROPOSED_ALGO+1];
 	char *work_list = m_strdup(user_algo_list);
-	char *last_name = work_list;
+	char *start = work_list;
 	char *c;
-	for (c = work_list; *c; c++)
+	int n;
+	/* So we can iterate and look for null terminator */
+	memset(new_algos, 0x0, sizeof(new_algos));
+	for (c = work_list, n = 0; ; c++)
 	{
-		if (*c == ',')
-		{
+		char oc = *c;
+		if (n >= MAX_PROPOSED_ALGO) {
+			dropbear_exit("Too many algorithms '%s'", user_algo_list);
+		}
+		if (*c == ',' || *c == '\0') {
+			algo_type *match_algo = NULL;
 			*c = '\0';
-			try_add_algo(last_name, algos, algo_desc, new_algos, &num_ret);
+			match_algo = check_algo(start, algos);
+			if (match_algo) {
+				if (check_algo(start, new_algos)) {
+					TRACE(("Skip repeated algorithm '%s'", start))
+				} else {
+					new_algos[n] = *match_algo;
+					n++;
+				}
+			} else {
+				dropbear_log(LOG_WARNING, "This Dropbear program does not support '%s' %s algorithm", start, algo_desc);
+			}
 			c++;
-			last_name = c;
+			start = c;
+		}
+		if (oc == '\0') {
+			break;
 		}
 	}
-	try_add_algo(last_name, algos, algo_desc, new_algos, &num_ret);
 	m_free(work_list);
-
-	new_algos[num_ret].name = NULL;
-
-	/* Copy one more as a blank delimiter */
-	memcpy(algos, new_algos, sizeof(*new_algos) * (num_ret+1));
-	return num_ret;
+	/* n+1 to include a null terminator */
+	memcpy(algos, new_algos, sizeof(*new_algos) * (n+1));
+	return n;
 }
 #endif /* DROPBEAR_USER_ALGO_LIST */
--- a/common-channel.c	Wed May 25 10:03:53 2016 -0500
+++ b/common-channel.c	Fri Jun 02 23:01:54 2017 +0800
@@ -32,7 +32,6 @@
 #include "circbuffer.h"
 #include "dbutil.h"
 #include "channel.h"
-#include "ssh.h"
 #include "listener.h"
 #include "runopts.h"
 #include "netio.h"
--- a/common-session.c	Wed May 25 10:03:53 2016 -0500
+++ b/common-session.c	Fri Jun 02 23:01:54 2017 +0800
@@ -361,7 +361,7 @@
 	}
 
 	if (!done) {
-		TRACE(("err: %s for '%s'\n", strerror(errno), linebuf))
+		TRACE(("error reading remote ident: %s\n", strerror(errno)))
 		ses.remoteclosed();
 	} else {
 		/* linebuf is already null terminated */
--- a/compat.c	Wed May 25 10:03:53 2016 -0500
+++ b/compat.c	Fri Jun 02 23:01:54 2017 +0800
@@ -114,8 +114,8 @@
 #endif /* HAVE_STRLCPY */
 
 #ifndef HAVE_STRLCAT
-/* taken from openbsd-compat for OpenSSH 3.6.1p1 */
-/* "$OpenBSD: strlcat.c,v 1.8 2001/05/13 15:40:15 deraadt Exp $"
+/* taken from openbsd-compat for OpenSSH 7.2p2 */
+/* "$OpenBSD: strlcat.c,v 1.13 2005/08/08 08:05:37 espie Exp $"
  *
  * Appends src to string dst of size siz (unlike strncat, siz is the
  * full size of dst, not space left).  At most siz-1 characters
@@ -123,15 +123,12 @@
  * Returns strlen(src) + MIN(siz, strlen(initial dst)).
  * If retval >= siz, truncation occurred.
  */
-	size_t
-strlcat(dst, src, siz)
-	char *dst;
-	const char *src;
-	size_t siz;
+size_t
+strlcat(char *dst, const char *src, size_t siz)
 {
-	register char *d = dst;
-	register const char *s = src;
-	register size_t n = siz;
+	char *d = dst;
+	const char *s = src;
+	size_t n = siz;
 	size_t dlen;
 
 	/* Find the end of dst and adjust bytes left but don't go past end */
@@ -177,7 +174,7 @@
 	if (!nochdir)
 		(void)chdir("/");
 
-	if (!noclose && (fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
+	if (!noclose && (fd = open(DROPBEAR_PATH_DEVNULL, O_RDWR, 0)) != -1) {
 		(void)dup2(fd, STDIN_FILENO);
 		(void)dup2(fd, STDOUT_FILENO);
 		(void)dup2(fd, STDERR_FILENO);
--- a/dbutil.c	Wed May 25 10:03:53 2016 -0500
+++ b/dbutil.c	Fri Jun 02 23:01:54 2017 +0800
@@ -182,7 +182,7 @@
 void dropbear_trace(const char* format, ...) {
 	va_list param;
 
-	if (!ses.debug_trace) {
+	if (!debug_trace) {
 		return;
 	}
 
@@ -681,4 +681,21 @@
 	return time(NULL);
 }
 
+void fsync_parent_dir(const char* fn) {
+#ifdef HAVE_LIBGEN_H
+	char *fn_dir = m_strdup(fn);
+	char *dir = dirname(fn_dir);
+	int dirfd = open(dir, O_RDONLY);
 
+	if (dirfd != -1) {
+		if (fsync(dirfd) != 0) {
+			TRACE(("fsync of directory %s failed: %s", dir, strerror(errno)))
+		}
+		m_close(dirfd);
+	} else {
+		TRACE(("error opening directory %s for fsync: %s", dir, strerror(errno)))
+	}
+
+	free(fn_dir);
+#endif
+}
--- a/dbutil.h	Wed May 25 10:03:53 2016 -0500
+++ b/dbutil.h	Fri Jun 02 23:01:54 2017 +0800
@@ -89,4 +89,6 @@
 
 char * expand_homedir_path(const char *inpath);
 
+void fsync_parent_dir(const char* fn);
+
 #endif /* DROPBEAR_DBUTIL_H_ */
--- a/debian/changelog	Wed May 25 10:03:53 2016 -0500
+++ b/debian/changelog	Fri Jun 02 23:01:54 2017 +0800
@@ -1,3 +1,15 @@
+dropbear (2017.75-0.1) unstable; urgency=low
+
+  * New upstream release.
+
+ -- Matt Johnston <[email protected]>  Thu, 18 May 2017 22:51:57 +0800
+
+dropbear (2016.74-0.1) unstable; urgency=low
+
+  * New upstream release.
+
+ -- Matt Johnston <[email protected]>  Thu, 21 Jul 2016 22:51:57 +0800
+
 dropbear (2016.73-0.1) unstable; urgency=low
 
   * New upstream release.
--- a/dropbearkey.c	Wed May 25 10:03:53 2016 -0500
+++ b/dropbearkey.c	Fri Jun 02 23:01:54 2017 +0800
@@ -241,7 +241,7 @@
 	}
 
 	fprintf(stderr, "Generating key, this may take a while...\n");
-	if (signkey_generate(keytype, bits, filename) == DROPBEAR_FAILURE)
+	if (signkey_generate(keytype, bits, filename, 0) == DROPBEAR_FAILURE)
 	{
 		dropbear_exit("Failed to generate key.\n");
 	}
--- a/gensignkey.c	Wed May 25 10:03:53 2016 -0500
+++ b/gensignkey.c	Fri Jun 02 23:01:54 2017 +0800
@@ -76,10 +76,12 @@
 	}
 }
 
-int signkey_generate(enum signkey_type keytype, int bits, const char* filename)
+/* if skip_exist is set it will silently return if the key file exists */
+int signkey_generate(enum signkey_type keytype, int bits, const char* filename, int skip_exist)
 {
 	sign_key * key = NULL;
 	buffer *buf = NULL;
+	char *fn_temp = NULL;
 	int ret = DROPBEAR_FAILURE;
 	if (bits == 0)
 	{
@@ -126,10 +128,37 @@
 	sign_key_free(key);
 	key = NULL;
 	buf_setpos(buf, 0);
-	ret = buf_writefile(buf, filename);
+
+	fn_temp = m_malloc(strlen(filename) + 30);
+	snprintf(fn_temp, strlen(filename)+30, "%s.tmp%d", filename, getpid());
+	ret = buf_writefile(buf, fn_temp);
+
+	if (ret == DROPBEAR_FAILURE) {
+		goto out;
+	}
 
-	buf_burn(buf);
-	buf_free(buf);
-	buf = NULL;
+	if (link(fn_temp, filename) < 0) {
+		/* If generating keys on connection (skipexist) it's OK to get EEXIST 
+		- we probably just lost a race with another connection to generate the key */
+		if (!(skip_exist && errno == EEXIST)) {
+			dropbear_log(LOG_ERR, "Failed moving key file to %s: %s", filename,
+				strerror(errno));
+			/* XXX fallback to non-atomic copy for some filesystems? */
+			ret = DROPBEAR_FAILURE;
+			goto out;
+		}
+	}
+
+out:
+	if (buf) {
+		buf_burn(buf);
+		buf_free(buf);
+	}
+	
+	if (fn_temp) {
+		unlink(fn_temp);
+		m_free(fn_temp);
+	}
+
 	return ret;
 }
--- a/gensignkey.h	Wed May 25 10:03:53 2016 -0500
+++ b/gensignkey.h	Fri Jun 02 23:01:54 2017 +0800
@@ -3,6 +3,6 @@
 
 #include "signkey.h"
 
-int signkey_generate(enum signkey_type type, int bits, const char* filename);
+int signkey_generate(enum signkey_type type, int bits, const char* filename, int skip_exist);
 
 #endif
--- a/keyimport.c	Wed May 25 10:03:53 2016 -0500
+++ b/keyimport.c	Fri Jun 02 23:01:54 2017 +0800
@@ -62,6 +62,8 @@
 static int dropbear_write(const char*filename, sign_key * key);
 static sign_key *dropbear_read(const char* filename);
 
+static int toint(unsigned u);
+
 #if 0
 static int sshcom_encrypted(const char *filename, char **comment);
 static struct ssh2_userkey *sshcom_read(const char *filename, char *passphrase);
@@ -243,12 +245,11 @@
 	if ((*p & 0x1F) == 0x1F) {
 		*id = 0;
 		while (*p & 0x80) {
-			*id = (*id << 7) | (*p & 0x7F);
 			p++, sourcelen--;
 			if (sourcelen == 0)
 				return -1;
+			*id = (*id << 7) | (*p & 0x7F);
 		}
-		*id = (*id << 7) | (*p & 0x7F);
 		p++, sourcelen--;
 	} else {
 		*id = *p & 0x1F;
@@ -259,19 +260,26 @@
 		return -1;
 
 	if (*p & 0x80) {
+		unsigned len;
 		int n = *p & 0x7F;
 		p++, sourcelen--;
 		if (sourcelen < n)
 			return -1;
-		*length = 0;
+		len = 0;
 		while (n--)
-			*length = (*length << 8) | (*p++);
+			len = (len << 8) | (*p++);
 		sourcelen -= n;
+		*length = toint(len);
 	} else {
 		*length = *p;
 		p++, sourcelen--;
 	}
 
+	if (*length < 0) {
+		printf("Negative ASN.1 length\n");
+		return -1;
+	}
+
 	return p - (unsigned char *) source;
 }
 
@@ -469,7 +477,7 @@
 	m_burn(buffer, sizeof(buffer));
 	return ret;
 
-	error:
+error:
 	m_burn(buffer, sizeof(buffer));
 	if (ret) {
 		if (ret->keyblob) {
@@ -584,8 +592,9 @@
 	/* Expect the SEQUENCE header. Take its absence as a failure to decrypt. */
 	ret = ber_read_id_len(p, key->keyblob_len, &id, &len, &flags);
 	p += ret;
-	if (ret < 0 || id != 16) {
-		errmsg = "ASN.1 decoding failure - wrong password?";
+	if (ret < 0 || id != 16 || len < 0 ||
+		key->keyblob+key->keyblob_len-p < len) {
+				errmsg = "ASN.1 decoding failure";
 		goto error;
 	}
 
@@ -619,7 +628,7 @@
 		ret = ber_read_id_len(p, key->keyblob+key->keyblob_len-p,
 							  &id, &len, &flags);
 		p += ret;
-		if (ret < 0 || id != 2 ||
+		if (ret < 0 || id != 2 || len < 0 ||
 			key->keyblob+key->keyblob_len-p < len) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
@@ -685,7 +694,7 @@
 							  &id, &len, &flags);
 		p += ret;
 		/* id==4 for octet string */
-		if (ret < 0 || id != 4 ||
+				if (ret < 0 || id != 4 || len < 0 ||
 			key->keyblob+key->keyblob_len-p < len) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
@@ -699,7 +708,7 @@
 							  &id, &len, &flags);
 		p += ret;
 		/* id==0 */
-		if (ret < 0 || id != 0) {
+				if (ret < 0 || id != 0 || len < 0) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
 		}
@@ -708,7 +717,7 @@
 							  &id, &len, &flags);
 		p += ret;
 		/* id==6 for object */
-		if (ret < 0 || id != 6 ||
+				if (ret < 0 || id != 6 || len < 0 ||
 			key->keyblob+key->keyblob_len-p < len) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
@@ -747,7 +756,7 @@
 							  &id, &len, &flags);
 		p += ret;
 		/* id==1 */
-		if (ret < 0 || id != 1) {
+				if (ret < 0 || id != 1 || len < 0) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
 		}
@@ -756,7 +765,7 @@
 							  &id, &len, &flags);
 		p += ret;
 		/* id==3 for bit string */
-		if (ret < 0 || id != 3 ||
+				if (ret < 0 || id != 3 || len < 0 ||
 			key->keyblob+key->keyblob_len-p < len) {
 			errmsg = "ASN.1 decoding failure";
 			goto error;
@@ -1381,7 +1390,7 @@
 			memset(ret->keyblob, 0, ret->keyblob_size);
 			m_free(ret->keyblob);
 		}
-		memset(&ret, 0, sizeof(ret));
+		memset(ret, 0, sizeof(*ret));
 		m_free(ret);
 	}
 	return NULL;
@@ -1409,11 +1418,12 @@
 	pos = 8;
 	if (key->keyblob_len < pos+4)
 		goto done;					 /* key is far too short */
-	pos += 4 + GET_32BIT(key->keyblob + pos);   /* skip key type */
-	if (key->keyblob_len < pos+4)
+	len = toint(GET_32BIT(key->keyblob + pos));
+	if (len < 0 || len > key->keyblob_len - pos - 4)
 		goto done;					 /* key is far too short */
-	len = GET_32BIT(key->keyblob + pos);   /* find cipher-type length */
-	if (key->keyblob_len < pos+4+len)
+	pos += 4 + len;                    /* skip key type */
+	len = toint(GET_32BIT(key->keyblob + pos)); /* find cipher-type length */
+	if (len < 0 || len > key->keyblob_len - pos - 4)
 		goto done;					 /* cipher type string is incomplete */
 	if (len != 4 || 0 != memcmp(key->keyblob + pos + 4, "none", 4))
 		answer = 1;
@@ -1422,15 +1432,14 @@
 	*comment = dupstr(key->comment);
 	memset(key->keyblob, 0, key->keyblob_size);
 	m_free(key->keyblob);
-	memset(&key, 0, sizeof(key));
+	memset(key, 0, sizeof(*key));
 	m_free(key);
 	return answer;
 }
 
 static int sshcom_read_mpint(void *data, int len, struct mpint_pos *ret)
 {
-	int bits;
-	int bytes;
+	unsigned bits, bytes;
 	unsigned char *d = (unsigned char *) data;
 
 	if (len < 4)
@@ -1483,7 +1492,7 @@
 	struct ssh2_userkey *ret = NULL, *retkey;
 	const struct ssh_signkey *alg;
 	unsigned char *blob = NULL;
-	int blobsize, publen, privlen;
+	int blobsize = 0, publen, privlen;
 
 	if (!key)
 		return NULL;
@@ -1603,8 +1612,8 @@
 	/*
 	 * Strip away the containing string to get to the real meat.
 	 */
-	len = GET_32BIT(ciphertext);
-	if (len > cipherlen-4) {
+	len = toint(GET_32BIT(ciphertext));
+	if (len < 0 || len > cipherlen-4) {
 		errmsg = "containing string was ill-formed";
 		goto error;
 	}
@@ -1671,7 +1680,8 @@
 		publen = pos;
 		pos += put_mp(blob+pos, x.start, x.bytes);
 		privlen = pos - publen;
-	}
+	} else
+		return NULL;
 
 	dropbear_assert(privlen > 0);			   /* should have bombed by now if not */
 
@@ -1695,7 +1705,7 @@
 	}
 	memset(key->keyblob, 0, key->keyblob_size);
 	m_free(key->keyblob);
-	memset(&key, 0, sizeof(key));
+	memset(key, 0, sizeof(*key));
 	m_free(key);
 	return ret;
 }
@@ -1908,3 +1918,27 @@
 	return ret;
 }
 #endif /* ssh.com stuff disabled */
+
+/* From PuTTY misc.c */
+static int toint(unsigned u)
+{
+	/*
+	 * Convert an unsigned to an int, without running into the
+	 * undefined behaviour which happens by the strict C standard if
+	 * the value overflows. You'd hope that sensible compilers would
+	 * do the sensible thing in response to a cast, but actually I
+	 * don't trust modern compilers not to do silly things like
+	 * assuming that _obviously_ you wouldn't have caused an overflow
+	 * and so they can elide an 'if (i < 0)' test immediately after
+	 * the cast.
+	 *
+	 * Sensible compilers ought of course to optimise this entire
+	 * function into 'just return the input value'!
+	 */
+	if (u <= (unsigned)INT_MAX)
+		return (int)u;
+	else if (u >= (unsigned)INT_MIN)   /* wrap in cast _to_ unsigned is OK */
+		return INT_MIN + (int)(u - (unsigned)INT_MIN);
+	else
+		return INT_MIN; /* fallback; should never occur on binary machines */
+}
--- a/libtommath/bn_mp_exteuclid.c	Wed May 25 10:03:53 2016 -0500
+++ b/libtommath/bn_mp_exteuclid.c	Fri Jun 02 23:01:54 2017 +0800
@@ -29,34 +29,34 @@
 
    /* initialize, (u1,u2,u3) = (1,0,a) */
    mp_set(&u1, 1);
-   if ((err = mp_copy(a, &u3)) != MP_OKAY)                                        { goto _ERR; }
+   if ((err = mp_copy(a, &u3)) != MP_OKAY)                                        { goto LBL_ERR; }
 
    /* initialize, (v1,v2,v3) = (0,1,b) */
    mp_set(&v2, 1);
-   if ((err = mp_copy(b, &v3)) != MP_OKAY)                                        { goto _ERR; }
+   if ((err = mp_copy(b, &v3)) != MP_OKAY)                                        { goto LBL_ERR; }
 
    /* loop while v3 != 0 */
    while (mp_iszero(&v3) == MP_NO) {
        /* q = u3/v3 */
-       if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY)                         { goto _ERR; }
+       if ((err = mp_div(&u3, &v3, &q, NULL)) != MP_OKAY)                         { goto LBL_ERR; }
 
        /* (t1,t2,t3) = (u1,u2,u3) - (v1,v2,v3)q */
-       if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
-       if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY)                             { goto _ERR; }
-       if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
-       if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY)                             { goto _ERR; }
-       if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY)                              { goto _ERR; }
-       if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY)                             { goto _ERR; }
+       if ((err = mp_mul(&v1, &q, &tmp)) != MP_OKAY)                              { goto LBL_ERR; }
+       if ((err = mp_sub(&u1, &tmp, &t1)) != MP_OKAY)                             { goto LBL_ERR; }
+       if ((err = mp_mul(&v2, &q, &tmp)) != MP_OKAY)                              { goto LBL_ERR; }
+       if ((err = mp_sub(&u2, &tmp, &t2)) != MP_OKAY)                             { goto LBL_ERR; }
+       if ((err = mp_mul(&v3, &q, &tmp)) != MP_OKAY)                              { goto LBL_ERR; }
+       if ((err = mp_sub(&u3, &tmp, &t3)) != MP_OKAY)                             { goto LBL_ERR; }
 
        /* (u1,u2,u3) = (v1,v2,v3) */
-       if ((err = mp_copy(&v1, &u1)) != MP_OKAY)                                  { goto _ERR; }
-       if ((err = mp_copy(&v2, &u2)) != MP_OKAY)                                  { goto _ERR; }
-       if ((err = mp_copy(&v3, &u3)) != MP_OKAY)                                  { goto _ERR; }
+       if ((err = mp_copy(&v1, &u1)) != MP_OKAY)                                  { goto LBL_ERR; }
+       if ((err = mp_copy(&v2, &u2)) != MP_OKAY)                                  { goto LBL_ERR; }
+       if ((err = mp_copy(&v3, &u3)) != MP_OKAY)                                  { goto LBL_ERR; }
 
        /* (v1,v2,v3) = (t1,t2,t3) */
-       if ((err = mp_copy(&t1, &v1)) != MP_OKAY)                                  { goto _ERR; }
-       if ((err = mp_copy(&t2, &v2)) != MP_OKAY)                                  { goto _ERR; }
-       if ((err = mp_copy(&t3, &v3)) != MP_OKAY)                                  { goto _ERR; }
+       if ((err = mp_copy(&t1, &v1)) != MP_OKAY)                                  { goto LBL_ERR; }
+       if ((err = mp_copy(&t2, &v2)) != MP_OKAY)                                  { goto LBL_ERR; }
+       if ((err = mp_copy(&t3, &v3)) != MP_OKAY)                                  { goto LBL_ERR; }
    }
 
    /* make sure U3 >= 0 */
@@ -72,7 +72,8 @@
    if (U3 != NULL) { mp_exch(U3, &u3); }
 
    err = MP_OKAY;
-_ERR: mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
+LBL_ERR:
+   mp_clear_multi(&u1, &u2, &u3, &v1, &v2, &v3, &t1, &t2, &t3, &q, &tmp, NULL);
    return err;
 }
 #endif
--- a/loginrec.c	Wed May 25 10:03:53 2016 -0500
+++ b/loginrec.c	Fri Jun 02 23:01:54 2017 +0800
@@ -706,7 +706,7 @@
 		}
 
 		(void)lseek(fd, (off_t)(tty * sizeof(struct utmp)), SEEK_SET);
-		if (atomicio(write, fd, ut, sizeof(*ut)) != sizeof(*ut))
+		if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut))
 			dropbear_log(LOG_WARNING, "utmp_write_direct: error writing %s: %s",
 			    UTMP_FILE, strerror(errno));
 
@@ -895,7 +895,7 @@
 		return 0;
 	}
 	if (fstat(fd, &buf) == 0)
-		if (atomicio(write, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
+		if (atomicio(vwrite, fd, ut, sizeof(*ut)) != sizeof(*ut)) {
 			ftruncate(fd, buf.st_size);
 			dropbear_log(LOG_WARNING, "wtmp_write: problem writing %s: %s",
 			    WTMP_FILE, strerror(errno));
@@ -1062,7 +1062,7 @@
 	}
 
 	if (fstat(fd, &buf) == 0)
-		if (atomicio(write, fd, utx, sizeof(*utx)) != sizeof(*utx)) {
+		if (atomicio(vwrite, fd, utx, sizeof(*utx)) != sizeof(*utx)) {
 			ftruncate(fd, buf.st_size);
 			dropbear_log(LOG_WARNING, "wtmpx_write: problem writing %s: %s",
 			    WTMPX_FILE, strerror(errno));
@@ -1351,7 +1351,7 @@
 		return(0);
 
 	/* write the entry */
-	if (atomicio(write, fd, &last, sizeof(last)) != sizeof(last)) {
+	if (atomicio(vwrite, fd, &last, sizeof(last)) != sizeof(last)) {
 		close(fd);
 		dropbear_log(LOG_WARNING, "lastlog_write_filemode: Error writing to %s: %s",
 		    LASTLOG_FILE, strerror(errno));
--- a/netio.c	Wed May 25 10:03:53 2016 -0500
+++ b/netio.c	Fri Jun 02 23:01:54 2017 +0800
@@ -61,7 +61,7 @@
 	{
 		dropbear_assert(c->sock == -1);
 
-		c->sock = socket(c->res_iter->ai_family, c->res_iter->ai_socktype, c->res_iter->ai_protocol);
+		c->sock = socket(r->ai_family, r->ai_socktype, r->ai_protocol);
 		if (c->sock < 0) {
 			continue;
 		}
--- a/scpmisc.c	Wed May 25 10:03:53 2016 -0500
+++ b/scpmisc.c	Fri Jun 02 23:01:54 2017 +0800
@@ -235,7 +235,7 @@
 {
 	int nullfd, dupfd;
 
-	if ((nullfd = dupfd = open(_PATH_DEVNULL, O_RDWR)) == -1) {
+	if ((nullfd = dupfd = open(DROPBEAR_PATH_DEVNULL, O_RDWR)) == -1) {
 		fprintf(stderr, "Couldn't open /dev/null: %s", strerror(errno));
 		exit(1);
 	}
--- a/scpmisc.h	Wed May 25 10:03:53 2016 -0500
+++ b/scpmisc.h	Fri Jun 02 23:01:54 2017 +0800
@@ -12,9 +12,6 @@
  * called by a name other than "ssh" or "Secure Shell".
  */
 
-/* actually from atomicio, but is only used in scp code */
-#define vwrite (ssize_t (*)(int, void *, size_t))write
-
 char	*chop(char *);
 char	*strdelim(char **);
 void	 set_nonblock(int);
--- a/svr-authpubkey.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-authpubkey.c	Fri Jun 02 23:01:54 2017 +0800
@@ -201,6 +201,8 @@
 	unsigned int len, pos;
 	buffer * options_buf = NULL;
 	int line_num;
+	uid_t origuid;
+	gid_t origgid;
 
 	TRACE(("enter checkpubkey"))
 
@@ -227,8 +229,21 @@
 	snprintf(filename, len + 22, "%s/.ssh/authorized_keys", 
 				ses.authstate.pw_dir);
 
-	/* open the file */
+	/* open the file as the authenticating user. */
+	origuid = getuid();
+	origgid = getgid();
+	if ((setegid(ses.authstate.pw_gid)) < 0 ||
+		(seteuid(ses.authstate.pw_uid)) < 0) {
+		dropbear_exit("Failed to set euid");
+	}
+
 	authfile = fopen(filename, "r");
+
+	if ((seteuid(origuid)) < 0 ||
+		(setegid(origgid)) < 0) {
+		dropbear_exit("Failed to revert euid");
+	}
+
 	if (authfile == NULL) {
 		goto out;
 	}
--- a/svr-authpubkeyoptions.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-authpubkeyoptions.c	Fri Jun 02 23:01:54 2017 +0800
@@ -95,6 +95,7 @@
 		if (chansess->cmd) {
 			/* original_command takes ownership */
 			chansess->original_command = chansess->cmd;
+			chansess->cmd = NULL;
 		} else {
 			chansess->original_command = m_strdup("");
 		}
@@ -108,6 +109,9 @@
 /* Free potential public key options */
 void svr_pubkey_options_cleanup() {
 	if (ses.authstate.pubkey_options) {
+		if (ses.authstate.pubkey_options->forced_command) {
+			m_free(ses.authstate.pubkey_options->forced_command);
+		}
 		m_free(ses.authstate.pubkey_options);
 		ses.authstate.pubkey_options = NULL;
 	}
@@ -200,8 +204,7 @@
 
 bad_option:
 	ret = DROPBEAR_FAILURE;
-	m_free(ses.authstate.pubkey_options);
-	ses.authstate.pubkey_options = NULL;
+	svr_pubkey_options_cleanup();
 	dropbear_log(LOG_WARNING, "Bad public key options at %s:%d", filename, line_num);
 
 end:
--- a/svr-chansession.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-chansession.c	Fri Jun 02 23:01:54 2017 +0800
@@ -634,7 +634,7 @@
 static int sessioncommand(struct Channel *channel, struct ChanSess *chansess,
 		int iscmd, int issubsys) {
 
-	unsigned int cmdlen;
+	unsigned int cmdlen = 0;
 	int ret;
 
 	TRACE(("enter sessioncommand"))
--- a/svr-kex.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-kex.c	Fri Jun 02 23:01:54 2017 +0800
@@ -93,29 +93,9 @@
 
 #if DROPBEAR_DELAY_HOSTKEY
 
-static void fsync_parent_dir(const char* fn) {
-#ifdef HAVE_LIBGEN_H
-	char *fn_dir = m_strdup(fn);
-	char *dir = dirname(fn_dir);
-	int dirfd = open(dir, O_RDONLY);
-
-	if (dirfd != -1) {
-		if (fsync(dirfd) != 0) {
-			TRACE(("fsync of directory %s failed: %s", dir, strerror(errno)))
-		}
-		m_close(dirfd);
-	} else {
-		TRACE(("error opening directory %s for fsync: %s", dir, strerror(errno)))
-	}
-
-	free(fn_dir);
-#endif
-}
-
 static void svr_ensure_hostkey() {
 
 	const char* fn = NULL;
-	char *fn_temp = NULL;
 	enum signkey_type type = ses.newkeys->algo_hostkey;
 	void **hostkey = signkey_key_ptr(svr_opts.hostkey, type);
 	int ret = DROPBEAR_FAILURE;
@@ -151,28 +131,10 @@
 		return;
 	}
 
-	fn_temp = m_malloc(strlen(fn) + 20);
-	snprintf(fn_temp, strlen(fn)+20, "%s.tmp%d", fn, getpid());
-
-	if (signkey_generate(type, 0, fn_temp) == DROPBEAR_FAILURE) {
+	if (signkey_generate(type, 0, fn, 1) == DROPBEAR_FAILURE) {
 		goto out;
 	}
-
-	if (link(fn_temp, fn) < 0) {
-		/* It's OK to get EEXIST - we probably just lost a race
-		with another connection to generate the key */
-		if (errno != EEXIST) {
-			dropbear_log(LOG_ERR, "Failed moving key file to %s: %s", fn,
-				strerror(errno));
-			/* XXX fallback to non-atomic copy for some filesystems? */
-			goto out;
-		}
-	}
-
-	/* ensure directory update is flushed to disk, otherwise we can end up
-	with zero-byte hostkey files if the power goes off */
-	fsync_parent_dir(fn);
-
+	
 	ret = readhostkey(fn, svr_opts.hostkey, &type);
 
 	if (ret == DROPBEAR_SUCCESS) {
@@ -190,11 +152,6 @@
 	}
 
 out:
-	if (fn_temp) {
-		unlink(fn_temp);
-		m_free(fn_temp);
-	}
-
 	if (ret == DROPBEAR_FAILURE)
 	{
 		dropbear_exit("Couldn't read or generate hostkey %s", fn);
--- a/svr-session.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-session.c	Fri Jun 02 23:01:54 2017 +0800
@@ -144,31 +144,33 @@
 
 /* failure exit - format must be <= 100 chars */
 void svr_dropbear_exit(int exitcode, const char* format, va_list param) {
-
-	char fmtbuf[300];
+	char exitmsg[150];
+	char fullmsg[300];
 	int i;
 
+	/* Render the formatted exit message */
+	vsnprintf(exitmsg, sizeof(exitmsg), format, param);
+
+	/* Add the prefix depending on session/auth state */
 	if (!sessinitdone) {
 		/* before session init */
-		snprintf(fmtbuf, sizeof(fmtbuf), 
-				"Early exit: %s", format);
+		snprintf(fullmsg, sizeof(fullmsg), "Early exit: %s", exitmsg);
 	} else if (ses.authstate.authdone) {
 		/* user has authenticated */
-		snprintf(fmtbuf, sizeof(fmtbuf),
+		snprintf(fullmsg, sizeof(fullmsg),
 				"Exit (%s): %s", 
-				ses.authstate.pw_name, format);
+				ses.authstate.pw_name, exitmsg);
 	} else if (ses.authstate.pw_name) {
 		/* we have a potential user */
-		snprintf(fmtbuf, sizeof(fmtbuf), 
+		snprintf(fullmsg, sizeof(fullmsg), 
 				"Exit before auth (user '%s', %u fails): %s",
-				ses.authstate.pw_name, ses.authstate.failcount, format);
+				ses.authstate.pw_name, ses.authstate.failcount, exitmsg);
 	} else {
 		/* before userauth */
-		snprintf(fmtbuf, sizeof(fmtbuf), 
-				"Exit before auth: %s", format);
+		snprintf(fullmsg, sizeof(fullmsg), "Exit before auth: %s", exitmsg);
 	}
 
-	_dropbear_log(LOG_INFO, fmtbuf, param);
+	dropbear_log(LOG_INFO, "%s", fullmsg);
 
 #if DROPBEAR_VFORK
 	/* For uclinux only the main server process should cleanup - we don't want
--- a/svr-tcpfwd.c	Wed May 25 10:03:53 2016 -0500
+++ b/svr-tcpfwd.c	Fri Jun 02 23:01:54 2017 +0800
@@ -199,7 +199,7 @@
 	}
 	else
 	{
-		tcpinfo->listenaddr = request_addr;
+		tcpinfo->listenaddr = m_strdup(request_addr);
 	}
 
 	ret = listen_tcpfwd(tcpinfo);
--- a/sysoptions.h	Wed May 25 10:03:53 2016 -0500
+++ b/sysoptions.h	Fri Jun 02 23:01:54 2017 +0800
@@ -4,7 +4,7 @@
  *******************************************************************/
 
 #ifndef DROPBEAR_VERSION
-#define DROPBEAR_VERSION "2016.73"
+#define DROPBEAR_VERSION "2017.75"
 #endif
 
 #define LOCAL_IDENT "SSH-2.0-dropbear_" DROPBEAR_VERSION