pidgin: 7e159eaa: Fix a crash bug in oscar related to tryi...

[markdoliner at pidgin.im]

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Revision: 7e159eaa14b0041fcc3ee5783cd1e4f2d039a1a1
Parent:   8e8ff246492e45af8f8d0808296d6f2906794dc0
Author:   markdoliner at pidgin.im
Date:     07/20/10 22:57:51
Branch:   im.pidgin.pidgin
URL: http://d.pidgin.im/viewmtn/revision/info/7e159eaa14b0041fcc3ee5783cd1e4f2d039a1a1

Changelog: 

Fix a crash bug in oscar related to trying to allocate too much memory.
This was reported to our security mailing list by Jan Kaluza The Great.
I honestly couldn't figure out how to repro this crash, so I've been
considering it as not a remote-crash security problem, so I chose to
skip the CVE process for this.

Changes against parent 8e8ff246492e45af8f8d0808296d6f2906794dc0

  patched  libpurple/protocols/oscar/oscar.c

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--- libpurple/protocols/oscar/oscar.c	d686e17a2818f4ebdc129959a65532808a727af1
+++ libpurple/protocols/oscar/oscar.c	4b8fce6e8b2d31a97ab97ded4d384a8227b066ba
@@ -3028,12 +3028,23 @@ incomingim_chan4(OscarData *od, FlapConn
 			if (smstype != 0)
 				break;
 			taglen = byte_stream_getle32(&qbs);
+			if (taglen > 2000) {
+				/* Avoid trying to allocate large amounts of memory, in
+				   case we get something unexpected. */
+				break;
+			}
 			tagstr = byte_stream_getstr(&qbs, taglen);
 			if (tagstr == NULL)
 				break;
 			byte_stream_advance(&qbs, 3);
 			byte_stream_advance(&qbs, 4);
 			smslen = byte_stream_getle32(&qbs);
+			if (smslen > 2000) {
+				/* Avoid trying to allocate large amounts of memory, in
+				   case we get something unexpected. */
+				g_free(tagstr);
+				break;
+			}
 			smsmsg = byte_stream_getstr(&qbs, smslen);
 
 			/* Check if this is an SMS being sent from server */