mirror/openssl
2
0
Fork 0
mirror of https://github.com/openssl/openssl.git synced 2024-11-21 01:15:20 +08:00
Code Issues Packages Projects Releases Wiki Activity

Limit the number of empty records that will be processed consecutively

Browse Source 
in order to prevent ssl3_get_record from never returning.

Reported by "oftc_must_be_destroyed" and George Kadianakis.
This commit is contained in:
Adam Langley 2013-02-20 12:42:09 -05:00 committed by Ben Laurie
parent a54a61e7a9
commit 64a786a292
3 changed files with 20 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

19
ssl/s3_pkt.c
View File

@ -272,6 +272,12 @@ int ssl3_read_n(SSL *s, int n, int max, int extend)
return(n);
}
/* MAX_EMPTY_RECORDS defines the number of consecutive, empty records that will
* be processed per call to ssl3_get_record. Without this limit an attacker
* could send empty records at a faster rate than we can process and cause
* ssl3_get_record to loop forever. */
#define MAX_EMPTY_RECORDS 32
/* Call this to get a new input record.
* It will return <= 0 if more data is needed, normally due to an error
* or non-blocking IO.
@ -292,6 +298,7 @@ static int ssl3_get_record(SSL *s)
short version;
unsigned mac_size;
size_t extra;
unsigned empty_record_count = 0;
rr= &(s->s3->rrec);
sess=s->session;
@ -522,7 +529,17 @@ printf("\n");
s->packet_length=0;
/* just read a 0 length packet */
if (rr->length == 0) goto again;
if (rr->length == 0)
{
empty_record_count++;
if (empty_record_count > MAX_EMPTY_RECORDS)
{
al=SSL_AD_UNEXPECTED_MESSAGE;
SSLerr(SSL_F_SSL3_GET_RECORD,SSL_R_TOO_MANY_EMPTY_FRAGMENTS);
goto f_err;
}
goto again;
}
#if 0
fprintf(stderr, "Ultimate Record type=%d, Length=%d\n", rr->type, rr->length);

1
ssl/ssl.h
View File

@ -2914,6 +2914,7 @@ void ERR_load_SSL_strings(void);
#define SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST 157
#define SSL_R_TLS_PEER_DID_NOT_RESPOND_WITH_CERTIFICATE_LIST 233
#define SSL_R_TLS_RSA_ENCRYPTED_VALUE_LENGTH_IS_WRONG 234
#define SSL_R_TOO_MANY_EMPTY_FRAGMENTS 388
#define SSL_R_TRIED_TO_USE_UNSUPPORTED_CIPHER 235
#define SSL_R_UNABLE_TO_DECODE_DH_CERTS 236
#define SSL_R_UNABLE_TO_DECODE_ECDH_CERTS 313

1
ssl/ssl_err.c
View File

@ -578,6 +578,7 @@ static ERR_STRING_DATA SSL_str_reasons[]=
{ERR_REASON(SSL_R_TLS_INVALID_ECPOINTFORMAT_LIST),"tls invalid ecpointformat list"},
{ERR_REASON(SSL_R_TLS_PEER_DID_NOT_RESPOND_WITH_CERTIFICATE_LIST),"tls peer did not respond with certificate list"},
{ERR_REASON(SSL_R_TLS_RSA_ENCRYPTED_VALUE_LENGTH_IS_WRONG),"tls rsa encrypted value length is wrong"},
{ERR_REASON(SSL_R_TOO_MANY_EMPTY_FRAGMENTS),"too many empty fragments"},
{ERR_REASON(SSL_R_TRIED_TO_USE_UNSUPPORTED_CIPHER),"tried to use unsupported cipher"},
{ERR_REASON(SSL_R_UNABLE_TO_DECODE_DH_CERTS),"unable to decode dh certs"},
{ERR_REASON(SSL_R_UNABLE_TO_DECODE_ECDH_CERTS),"unable to decode ecdh certs"},