mirrors/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2024-09-30 06:10:56 +00:00
Code Issues Releases Wiki Activity

bpf: Avoid splat in pskb_pull_reason

Browse source 
[ Upstream commit 2bbe3e5a2f ]

syzkaller builds (CONFIG_DEBUG_NET=y) frequently trigger a debug
hint in pskb_may_pull.

We'd like to retain this debug check because it might hint at integer
overflows and other issues (kernel code should pull headers, not huge
value).

In bpf case, this splat isn't interesting at all: such (nonsensical)
bpf programs are typically generated by a fuzzer anyway.

Do what Eric suggested and suppress such warning.

For CONFIG_DEBUG_NET=n we don't need the extra check because
pskb_may_pull will do the right thing: return an error without the
WARN() backtrace.

Fixes: 219eee9c0d ("net: skbuff: add overflow debug check to pull/push helpers")
Reported-by: syzbot+0c4150bff9fff3bf023c@syzkaller.appspotmail.com
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://syzkaller.appspot.com/bug?extid=0c4150bff9fff3bf023c
Link: https://lore.kernel.org/netdev/9f254c96-54f2-4457-b7ab-1d9f6187939c@gmail.com/
Link: https://lore.kernel.org/bpf/20240614101801.9496-1-fw@strlen.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Florian Westphal 2024-06-14 12:17:33 +02:00 committed by Greg Kroah-Hartman
parent 7dabc4b45b
commit dacc15e9cb
1 changed files with 5 additions and 0 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

5
net/core/filter.c
View file

@ -1655,6 +1655,11 @@ static DEFINE_PER_CPU(struct bpf_scratchpad, bpf_sp);
static inline int __bpf_try_make_writable(struct sk_buff *skb,
unsigned int write_len)
{
#ifdef CONFIG_DEBUG_NET
/* Avoid a splat in pskb_may_pull_reason() */
if (write_len > INT_MAX)
return -EINVAL;
#endif
return skb_ensure_writable(skb, write_len);
}