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 23:18:51 +0100 |
| commit | baaabfd8fdcec04a691695fad9a664bea43202b6 (patch) | |
| tree | e3cc3e3b9ad784fdcfb27589b843bfbab0f9bf02 | |
| parent | 3cb28d188803c7768f767f0da40bbea61449521c (diff) | |
| download | openssl-baaabfd8fdcec04a691695fad9a664bea43202b6.tar.gz | |
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>
| -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 7d322d0253..fbcf2e663c 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -3401,9 +3401,7 @@ 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); @@ -3437,6 +3435,13 @@ 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 |