Commit 5a19f9ea authored by Matt Caswell's avatar Matt Caswell
Browse files

Sanity check the ticket length before using key name/IV 



This could in theory result in an overread - but due to the over allocation
of the underlying buffer does not represent a security issue.

Thanks to Fedor Indutny for reporting this issue.

Reviewed-by: default avatarRich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5415)
parent 058f12b7

ssl/t1_lib.c

+11 −5
Original line number Diff line number Diff line
@@ -3111,9 +3111,15 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, 
    int slen, mlen, renew_ticket = 0, ret = -1;

    unsigned char tick_hmac[EVP_MAX_MD_SIZE];

    HMAC_CTX *hctx = NULL;

    EVP_CIPHER_CTX *ctx;

    EVP_CIPHER_CTX *ctx = NULL;

    SSL_CTX *tctx = s->session_ctx;



    /* Need at least keyname + iv */

    if (eticklen < TLSEXT_KEYNAME_LENGTH + EVP_MAX_IV_LENGTH) {

        ret = 2;

        goto err;

    }



    /* Initialize session ticket encryption and HMAC contexts */

    hctx = HMAC_CTX_new();

    if (hctx == NULL)
@@ -3125,7 +3131,8 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, 
    }

    if (tctx->tlsext_ticket_key_cb) {

        unsigned char *nctick = (unsigned char *)etick;

        int rv = tctx->tlsext_ticket_key_cb(s, nctick, nctick + 16,

        int rv = tctx->tlsext_ticket_key_cb(s, nctick,

                                            nctick + TLSEXT_KEYNAME_LENGTH,

                                            ctx, hctx, 0);

        if (rv < 0)

            goto err;
@@ -3138,7 +3145,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, 
    } else {

        /* Check key name matches */

        if (memcmp(etick, tctx->tlsext_tick_key_name,

                   sizeof(tctx->tlsext_tick_key_name)) != 0) {

                   TLSEXT_KEYNAME_LENGTH) != 0) {

            ret = 2;

            goto err;

        }
@@ -3147,8 +3154,7 @@ static int tls_decrypt_ticket(SSL *s, const unsigned char *etick, 
                         EVP_sha256(), NULL) <= 0

            || EVP_DecryptInit_ex(ctx, EVP_aes_256_cbc(), NULL,

                                  tctx->tlsext_tick_aes_key,

                                  etick + sizeof(tctx->tlsext_tick_key_name)) <=

            0) {

                                  etick + TLSEXT_KEYNAME_LENGTH) <= 0) {

            goto err;

        }

    }