diff options
author | Adam Langley <agl@chromium.org> | 2013-02-20 12:42:09 -0500 |
---|---|---|
committer | Ben Laurie <ben@links.org> | 2013-06-13 17:10:52 +0100 |
commit | 64a786a292e301bfbcb269cd2bff0533503d5b8b (patch) | |
tree | e29666df61fdc0bf9a52998f09ad3bcac1b09d4c /ssl/s3_pkt.c | |
parent | a54a61e7a94466f4dc1d663a4297bca562d1a5ac (diff) | |
download | openssl-64a786a292e301bfbcb269cd2bff0533503d5b8b.tar.gz |
Limit the number of empty records that will be processed consecutively
in order to prevent ssl3_get_record from never returning.
Reported by "oftc_must_be_destroyed" and George Kadianakis.
Diffstat (limited to 'ssl/s3_pkt.c')
-rw-r--r-- | ssl/s3_pkt.c | 19 |
1 files changed, 18 insertions, 1 deletions
diff --git a/ssl/s3_pkt.c b/ssl/s3_pkt.c index 80562914f0..e589409906 100644 --- a/ssl/s3_pkt.c +++ b/ssl/s3_pkt.c @@ -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); |