diff options
Diffstat (limited to 'lib/libc/gen/syslog.3')
| -rw-r--r-- | lib/libc/gen/syslog.3 | 20 |
1 files changed, 19 insertions, 1 deletions
diff --git a/lib/libc/gen/syslog.3 b/lib/libc/gen/syslog.3 index 3dc53dd111c..f7e48e952f1 100644 --- a/lib/libc/gen/syslog.3 +++ b/lib/libc/gen/syslog.3 @@ -1,4 +1,4 @@ -.\" $OpenBSD: syslog.3,v 1.7 1999/07/09 13:35:19 aaron Exp $ +.\" $OpenBSD: syslog.3,v 1.8 2000/07/16 22:44:58 millert Exp $ .\" .\" Copyright (c) 1985, 1991, 1993 .\" The Regents of the University of California. All rights reserved. @@ -269,3 +269,21 @@ syslog(LOG_INFO|LOG_LOCAL2, "foobar error: %m"); These functions appeared in .Bx 4.2 . +.Sh CAVEATS +It is important to never pass a string with user-supplied data as a +format without using %s. +An attacker can put format specifiers in the string to mangle your stack, +leading to a possible security hole. +This holds true even if you have built the string +.Dq by hand +using a function like +.Fn snprintf , +as the attacker can escape the percent sign +.Pq Sq % +for later interpolation by +.Fn syslog . +.Pp +Be sure to always use the proper secure idiom: +.Bd -literal -offset indent +syslog("%s", string); +.Ed |