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Fix for DTLS DoS issue introduced by fix for CVE-2011-4109.

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Thanks to Antonio Martin, Enterprise Secure Access Research and
Development, Cisco Systems, Inc. for discovering this bug and
preparing a fix. (CVE-2012-0050)
This commit is contained in:
Dr. Stephen Henson
2012-01-18 13:12:08 +00:00
parent cc10bcf25e
commit 096327a99a
2 changed files with 12 additions and 11 deletions
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17
ssl/d1_pkt.c
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@@ -336,6 +336,7 @@ dtls1_process_record(SSL *s)
unsigned int mac_size;
unsigned char md[EVP_MAX_MD_SIZE];
int decryption_failed_or_bad_record_mac = 0;
unsigned char *mac = NULL;
rr= &(s->s3->rrec);
@@ -403,19 +404,15 @@ if ( (sess == NULL) ||
#endif
}
/* check the MAC for rr->input (it's in mac_size bytes at the tail) */
if (rr->length < mac_size)
if (rr->length >= mac_size)
{
#if 0 /* OK only for stream ciphers */
al=SSL_AD_DECODE_ERROR;
SSLerr(SSL_F_DTLS1_PROCESS_RECORD,SSL_R_LENGTH_TOO_SHORT);
goto f_err;
#else
decryption_failed_or_bad_record_mac = 1;
#endif
rr->length -= mac_size;
mac = &rr->data[rr->length];
}
rr->length-=mac_size;
else
rr->length = 0;
s->method->ssl3_enc->mac(s,md,0);
if (memcmp(md,&(rr->data[rr->length]),mac_size) != 0)
if (mac == NULL || memcmp(md, mac, mac_size) != 0)
{
decryption_failed_or_bad_record_mac = 1;
}