diff options
| author | Dr. Stephen Henson <steve@openssl.org> | 2016-08-22 17:20:01 +0100 |
|---|---|---|
| committer | Matt Caswell <matt@openssl.org> | 2016-08-23 23:16:24 +0100 |
| commit | e97763c92c655dcf4af2860b3abd2bc4c8a267f9 (patch) | |
| tree | 7685c3cebdb14bafe73c9eb5c3fd8c7a1f761043 /ssl | |
| parent | 652c52a602b4c88cfadb99e85ef175441b7f5d18 (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: Viktor Dukhovni <viktor@openssl.org>
Diffstat (limited to 'ssl')
| -rw-r--r-- | ssl/t1_lib.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/ssl/t1_lib.c b/ssl/t1_lib.c index 938f8be15f..b8f8fd22fe 100644 --- a/ssl/t1_lib.c +++ b/ssl/t1_lib.c @@ -2969,9 +2969,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, HMAC_CTX *hctx = NULL; 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 */ hctx = HMAC_CTX_new(); if (hctx == NULL) @@ -3018,6 +3016,12 @@ 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 <= + TLSEXT_KEYNAME_LENGTH + EVP_CIPHER_CTX_iv_length(ctx) + mlen) { + ret = 2; + goto err; + } eticklen -= mlen; /* Check HMAC of encrypted ticket */ if (HMAC_Update(hctx, etick, eticklen) <= 0 |