annotate fuzzer-kexecdh.c @ 1593:c8c20fb57a9a

Don't read uninitialised value. From https://github.com/libtom/libtommath/commit/1d03522625f46214733e8e143a4765c01fc146f9
author Matt Johnston <matt@ucc.asn.au>
date Mon, 05 Mar 2018 16:50:24 +0800
parents 46506b32650a
children 4fe7cc9e45eb
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1 #include "fuzz.h"
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2 #include "session.h"
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3 #include "fuzz-wrapfd.h"
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4 #include "debug.h"
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5 #include "runopts.h"
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6 #include "algo.h"
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7 #include "bignum.h"
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8
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9 int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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10 static int once = 0;
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11 static const struct dropbear_kex *ecdh[3]; /* 256, 384, 521 */
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12 static struct key_context* keep_newkeys = NULL;
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13 /* number of generated parameters is limited by the timeout for the first run */
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14 #define NUM_PARAMS 300
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15 static struct kex_ecdh_param *ecdh_params[NUM_PARAMS];
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16
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17 if (!once) {
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18 fuzz_common_setup();
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19 fuzz_svr_setup();
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20
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21 /* ses gets zeroed by fuzz_set_input */
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22 keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context));
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23 ecdh[0] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp256");
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24 ecdh[1] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp384");
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25 ecdh[2] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp521");
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26 assert(ecdh[0]);
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27 assert(ecdh[1]);
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28 assert(ecdh[2]);
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29 keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ECDSA_NISTP256;
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30 ses.newkeys = keep_newkeys;
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31
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32 /* Pre-generate parameters */
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33 int i;
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34 for (i = 0; i < NUM_PARAMS; i++) {
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35 ses.newkeys->algo_kex = ecdh[i % 3];
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36 ecdh_params[i] = gen_kexecdh_param();
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37 }
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38
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39 once = 1;
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40 }
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41
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42 if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) {
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43 return 0;
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44 }
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45
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46 m_malloc_set_epoch(1);
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47
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48 if (setjmp(fuzz.jmp) == 0) {
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49 /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply()
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50 with DROPBEAR_KEX_ECDH */
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51 ses.newkeys = keep_newkeys;
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52
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53 /* random choice of ecdh 256, 384, 521 */
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54 unsigned char b = buf_getbyte(fuzz.input);
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55 ses.newkeys->algo_kex = ecdh[b % 3];
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56
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57 /* Choose from the collection of ecdh params */
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58 unsigned int e = buf_getint(fuzz.input);
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59 struct kex_ecdh_param *ecdh_param = ecdh_params[e % NUM_PARAMS];
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60
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61 buffer * ecdh_qs = buf_getstringbuf(fuzz.input);
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62
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63 ses.kexhashbuf = buf_new(4);
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64 buf_putint(ses.kexhashbuf, 12345);
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65 kexecdh_comb_key(ecdh_param, ecdh_qs, svr_opts.hostkey);
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66
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67 /* kexhashbuf is freed in kexdh_comb_key */
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68 m_free(ses.dh_K);
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69 buf_free(ecdh_qs);
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70
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71 m_malloc_free_epoch(1, 0);
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72 } else {
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73 m_malloc_free_epoch(1, 1);
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74 TRACE(("dropbear_exit longjmped"))
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75 /* dropbear_exit jumped here */
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76 }
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77
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78 return 0;
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79 }