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* parse-packet.c (parse_user_id): Cap the user ID size at 2048 bytes.

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This prevents a memory allocation attack with a very large user ID.  A
very large packet length could even cause the allocation (a u32) to wrap
around to a small number.  Noted by Evgeny Legerov on full-disclosure.
This commit is contained in:
David Shaw 2006-06-09 19:45:19 +00:00
parent 49c31957f0
commit 91dbfce3b7
2 changed files with 22 additions and 0 deletions
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8
g10/ChangeLog
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@ -1,3 +1,11 @@
2006-06-09 David Shaw <dshaw@jabberwocky.com>
* parse-packet.c (parse_user_id): Cap the user ID size at 2048
bytes. This prevents a memory allocation attack with a very large
user ID. A very large packet length could even cause the
allocation (a u32) to wrap around to a small number. Noted by
Evgeny Legerov on full-disclosure.
2006-05-25 David Shaw <dshaw@jabberwocky.com>
* keygen.c (gen_dsa): Allow generating DSA2 keys

14
g10/parse-packet.c
View File

@ -1982,6 +1982,20 @@ parse_user_id( IOBUF inp, int pkttype, unsigned long pktlen, PACKET *packet )
{
byte *p;
/* Cap the size of a user ID at 2k: a value absurdly large enough
that there is no sane user ID string (which is printable text
as of RFC2440bis) that won't fit in it, but yet small enough to
avoid allocation problems. A large pktlen may not be
allocatable, and a very large pktlen could actually cause our
allocation to wrap around in xmalloc to a small number. */
if(pktlen>2048)
{
log_error("packet(%d) too large\n", pkttype);
iobuf_skip_rest(inp, pktlen, 0);
return G10ERR_INVALID_PACKET;
}
packet->pkt.user_id = xmalloc_clear(sizeof *packet->pkt.user_id + pktlen);
packet->pkt.user_id->len = pktlen;
packet->pkt.user_id->ref=1;