OpenSSH Security Advisory: buffer.adv

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Date: Tuesday, September 16, 2003 - 8:32 am

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 */
 }
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Messages in current thread:
BSDCan 2005 - call for papers, Dan Langille, (Thu Dec 2, 12:36 am)
Microsoft to base next generation OS on OpenBSD, Minister of Propaganda, (Sun Mar 31, 11:38 pm)
OpenSSH Security Advisory (adv.iss), Markus Friedl, (Wed Jun 26, 10:41 am)
OpenBSD 3.3 released, Todd C. Miller, (Wed Apr 30, 9:56 pm)
OpenSSH Security Advisory: buffer.adv, Markus Friedl, (Tue Sep 16, 8:32 am)