OpenSSH Buffer Management Bug Advisory
The following advisory is listed on the OpenSSH security page. It was up
some time ago before disappearing for a while and then reappearing in the
last few minutes.
---
Subject: OpenSSH Security Advisory: buffer.adv
This is the 1st revision of the Advisory.
This document can be found at: http://www.openssh.com/txt/buffer.adv
1. Versions affected:
All versions of OpenSSH's sshd prior to 3.7 contain a buffer
management error. It is uncertain whether this error is
potentially exploitable, however, we prefer to see bugs
fixed proactively.
2. Solution:
Upgrade to OpenSSH 3.7 or apply the following patch.
Appendix:
Index: buffer.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/buffer.c,v
retrieving revision 1.16
retrieving revision 1.17
diff -u -r1.16 -r1.17
--- buffer.c 26 Jun 2002 08:54:18 -0000 1.16
+++ buffer.c 16 Sep 2003 03:03:47 -0000 1.17
@@ -69,6 +69,7 @@
void *
buffer_append_space(Buffer *buffer, u_int len)
{
+ u_int newlen;
void *p;
if (len > 0x100000)
@@ -98,11 +99,13 @@
goto restart;
}
/* Increase the size of the buffer and retry. */
- buffer->alloc += len + 32768;
- if (buffer->alloc > 0xa00000)
+
+ newlen = buffer->alloc + len + 32768;
+ if (newlen > 0xa00000)
fatal("buffer_append_space: alloc %u not supported",
- buffer->alloc);
- buffer->buf = xrealloc(buffer->buf, buffer->alloc);
+ newlen);
+ buffer->buf = xrealloc(buffer->buf, newlen);
+ buffer->alloc = newlen;
goto restart;
/* NOTREACHED */
}
David Mirza Ahmad
Symantec
PGP: 0x26005712
8D 9A B1 33 82 3D B3 D0 40 EB AB F0 1E 67 C6 1A 26 00 57 12
--
The battle for the past is for the future.
We must be the winners of the memory war.