#include "fuzz.h" #include "session.h" #include "fuzz-wrapfd.h" #include "debug.h" #include "runopts.h" #include "algo.h" #include "bignum.h" static const struct dropbear_kex *ecdh[3]; /* 256, 384, 521 */ static struct key_context* keep_newkeys = NULL; /* number of generated parameters. An arbitrary limit, but will delay startup */ #define NUM_PARAMS 80 static struct kex_ecdh_param *ecdh_params[NUM_PARAMS]; static void setup() __attribute__((constructor)); // Perform initial setup here to avoid hitting timeouts on first run static void setup() { fuzz_common_setup(); fuzz_svr_setup(); /* ses gets zeroed by fuzz_set_input */ keep_newkeys = (struct key_context*)m_malloc(sizeof(struct key_context)); ecdh[0] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp256"); ecdh[1] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp384"); ecdh[2] = fuzz_get_algo(sshkex, "ecdh-sha2-nistp521"); assert(ecdh[0]); assert(ecdh[1]); assert(ecdh[2]); keep_newkeys->algo_hostkey = DROPBEAR_SIGNKEY_ECDSA_NISTP256; ses.newkeys = keep_newkeys; /* Pre-generate parameters */ int i; for (i = 0; i < NUM_PARAMS; i++) { ses.newkeys->algo_kex = ecdh[i % 3]; ecdh_params[i] = gen_kexecdh_param(); } } int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) { if (fuzz_set_input(Data, Size) == DROPBEAR_FAILURE) { return 0; } m_malloc_set_epoch(1); if (setjmp(fuzz.jmp) == 0) { /* Based on recv_msg_kexdh_init()/send_msg_kexdh_reply() with DROPBEAR_KEX_ECDH */ ses.newkeys = keep_newkeys; /* random choice of ecdh 256, 384, 521 */ unsigned char b = buf_getbyte(fuzz.input); ses.newkeys->algo_kex = ecdh[b % 3]; /* Choose from the collection of ecdh params */ unsigned int e = buf_getint(fuzz.input); struct kex_ecdh_param *ecdh_param = ecdh_params[e % NUM_PARAMS]; buffer * ecdh_qs = buf_getstringbuf(fuzz.input); ses.kexhashbuf = buf_new(KEXHASHBUF_MAX_INTS); kexecdh_comb_key(ecdh_param, ecdh_qs, svr_opts.hostkey); mp_clear(ses.dh_K); m_free(ses.dh_K); buf_free(ecdh_qs); buf_free(ses.hash); buf_free(ses.session_id); /* kexhashbuf is freed in kexdh_comb_key */ m_malloc_free_epoch(1, 0); } else { m_malloc_free_epoch(1, 1); TRACE(("dropbear_exit longjmped")) /* dropbear_exit jumped here */ } return 0; }