Module Name: src
Committed By: maxv
Date: Fri Sep 13 06:39:29 UTC 2019
Modified Files:
src/sys/net: bpf.c
Log Message:
As I suspected, the KASSERT I added yesterday can fire if we try to process
zero-sized packets. Skip them to prevent a type confusion that can trigger
random page faults later.
Reported-by: syzbot+3e447ebdcb2bcfa40...@syzkaller.appspotmail.com
To generate a diff of this commit:
cvs rdiff -u -r1.230 -r1.231 src/sys/net/bpf.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/net/bpf.c
diff -u src/sys/net/bpf.c:1.230 src/sys/net/bpf.c:1.231
--- src/sys/net/bpf.c:1.230 Thu Sep 12 07:38:19 2019
+++ src/sys/net/bpf.c Fri Sep 13 06:39:29 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: bpf.c,v 1.230 2019/09/12 07:38:19 maxv Exp $ */
+/* $NetBSD: bpf.c,v 1.231 2019/09/13 06:39:29 maxv Exp $ */
/*
* Copyright (c) 1990, 1991, 1993
@@ -39,7 +39,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: bpf.c,v 1.230 2019/09/12 07:38:19 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: bpf.c,v 1.231 2019/09/13 06:39:29 maxv Exp $");
#if defined(_KERNEL_OPT)
#include "opt_bpf.h"
@@ -1676,6 +1676,11 @@ _bpf_mtap(struct bpf_if *bp, struct mbuf
pktlen = m_length(m);
+ /* Skip zero-sized packets. */
+ if (__predict_false(pktlen == 0)) {
+ return;
+ }
+
if (pktlen == m->m_len) {
cpfn = (void *)memcpy;
marg = mtod(m, void *);
