diff options
| author | Dr. Stephen Henson <steve@openssl.org> | 2016-08-23 18:14:54 +0100 |
|---|---|---|
| committer | Matt Caswell <matt@openssl.org> | 2016-08-23 23:34:07 +0100 |
| commit | 1bbe48ab149893a78bf99c8eb8895c928900a16f (patch) | |
| tree | 3298dae3507b0bdd7e08608f7fc35ae7af37af81 | |
| parent | 3612ff6fcec0e3d1f2a598135fe12177c0419582 (diff) | |
Sanity check ticket length.
If a ticket callback changes the HMAC digest to SHA512 the existing
sanity checks are not sufficient and an attacker could perform a DoS
attack with a malformed ticket. Add additional checks based on
HMAC size.
Thanks to Shi Lei for reporting this bug.
CVE-2016-6302
Reviewed-by: Rich Salz <rsalz@openssl.org>
(cherry picked from commit baaabfd8fdcec04a691695fad9a664bea43202b6)
| -rw-r--r-- | ssl/t1_lib.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index d961e4afb5..7680491340 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -2273,9 +2273,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, HMAC_CTX hctx; EVP_CIPHER_CTX ctx; SSL_CTX *tctx = s->initial_ctx; - /* Need at least keyname + iv + some encrypted data */ - if (eticklen < 48) - return 2; + /* Initialize session ticket encryption and HMAC contexts */ HMAC_CTX_init(&hctx); EVP_CIPHER_CTX_init(&ctx); @@ -2309,6 +2307,13 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, if (mlen < 0) { goto err; } + /* Sanity check ticket length: must exceed keyname + IV + HMAC */ + if (eticklen <= 16 + EVP_CIPHER_CTX_iv_length(&ctx) + mlen) { + HMAC_CTX_cleanup(&hctx); + EVP_CIPHER_CTX_cleanup(&ctx); + return 2; + } + eticklen -= mlen; /* Check HMAC of encrypted ticket */ if (HMAC_Update(&hctx, etick, eticklen) <= 0 |