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crypto/hmac_drbg: Fix buffer overflow.

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This commit is contained in:
Andrew Kozlik 2019-06-09 21:03:14 +02:00
parent c2bdd1cf32
commit 013929de0b
2 changed files with 13 additions and 8 deletions
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4
crypto/hmac_drbg.c
View File

@ -118,9 +118,9 @@ void hmac_drbg_generate(HMAC_DRBG_CTX *ctx, uint8_t *buf, size_t len) {
size_t i = 0;
while (i < len) {
update_v(ctx);
for (size_t j = 0; j < 8; j++) {
for (size_t j = 0; j < 8 && i < len; j++) {
uint32_t r = ctx->v[j];
for (int k = 24; k >= 0; k -= 8) {
for (int k = 24; k >= 0 && i < len; k -= 8) {
buf[i++] = (r >> k) & 0xFF;
}
}

17
crypto/tests/test_check.c
View File

@ -4637,6 +4637,7 @@ START_TEST(test_hmac_drbg) {
"c3e66ea1b1a064b005de914eac2e9d4f2d72a8616a80225422918250ff66a41bd2f864a6"
"a38cc5b6499dc43f7f2bd09e1e0f8f5885935124";
uint8_t result[128];
uint8_t null_bytes[128] = {0};
uint8_t nonce_bytes[16];
memcpy(nonce_bytes, fromhex(nonce), sizeof(nonce_bytes));
@ -4648,12 +4649,16 @@ START_TEST(test_hmac_drbg) {
hmac_drbg_generate(&ctx, result, sizeof(result));
ck_assert_mem_eq(result, fromhex(expected), sizeof(result));
hmac_drbg_init(&ctx, fromhex(entropy), strlen(entropy) / 2, nonce_bytes,
strlen(nonce) / 2);
hmac_drbg_reseed(&ctx, fromhex(reseed), strlen(reseed) / 2, NULL, 0);
hmac_drbg_generate(&ctx, result, sizeof(result) - 13);
hmac_drbg_generate(&ctx, result, sizeof(result) - 17);
ck_assert_mem_eq(result, fromhex(expected), sizeof(result) - 17);
for (size_t i = 0; i <= sizeof(result); ++i) {
hmac_drbg_init(&ctx, fromhex(entropy), strlen(entropy) / 2, nonce_bytes,
strlen(nonce) / 2);
hmac_drbg_reseed(&ctx, fromhex(reseed), strlen(reseed) / 2, NULL, 0);
hmac_drbg_generate(&ctx, result, sizeof(result) - 13);
memset(result, 0, sizeof(result));
hmac_drbg_generate(&ctx, result, i);
ck_assert_mem_eq(result, fromhex(expected), i);
ck_assert_mem_eq(result + i, null_bytes, sizeof(result) - i);
}
}
END_TEST