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-rw-r--r--fuzzer-kexecdh.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/fuzzer-kexecdh.c b/fuzzer-kexecdh.c
new file mode 100644
index 0000000..c3a450a
--- /dev/null
+++ b/fuzzer-kexecdh.c
@@ -0,0 +1,82 @@
+#include "fuzz.h"
+#include "session.h"
+#include "fuzz-wrapfd.h"
+#include "debug.h"
+#include "runopts.h"
+#include "algo.h"
+#include "bignum.h"
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+ static int once = 0;
+ static const struct dropbear_kex *ecdh[3]; /* 256, 384, 521 */
+ static struct key_context* keep_newkeys = NULL;
+ /* number of generated parameters is limited by the timeout for the first run */
+ #define NUM_PARAMS 80
+ static struct kex_ecdh_param *ecdh_params[NUM_PARAMS];
+
+ if (!once) {
+ 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();
+ }
+
+ once = 1;
+ }
+
+ 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;
+}