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Date: Wed, 21 Jun 2000 22:30:23 +0200 (CEST)
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Subject: bin/19422: buffer overflow in ps
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>Number:         19422
>Category:       bin
>Synopsis:       users can overflow argv to make ps segfault
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Wed Jun 21 13:40:01 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     Marc Olzheim
>Release:        FreeBSD 3.4-RELEASE i386
>Organization:
M.C.G.V. Stack
>Environment:

Doesn't matter.

>Description:

When a user reset his argv[0] within a program to a string, with a size larger
than sysconf(_SC_ARG_MAX), ps does not prevent it from overflowing an internal
buffer with strvis.

>How-To-Repeat:

A program that does argv[0] = blah; , where blah is a string, longer than
sysconf(_SC_ARG_MAX), and keeps waiting. Then just run 'ps wwwaxuU <user>'
and chances are ps segfaults.

>Fix:
	
--- /usr/src/bin/ps/fmt.c	Sat Aug 28 01:14:51 1999
+++ /usr/src/bin/ps/fmt.c	Wed Jun 21 22:19:22 2000
@@ -80,7 +80,7 @@
 	for (p = argv; (src = *p++) != 0; ) {
 		if (*src == 0)
 			continue;
-		strvis(dst, src, VIS_NL | VIS_CSTYLE);
+		strvisx(dst, src, arg_max - strlen(buf) - 1, VIS_NL | VIS_CSTYLE);
 		while (*dst)
 			dst++;
 		*dst++ = ' ';

>Release-Note:
>Audit-Trail:
>Unformatted:


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