From: Florian Westphal <fw@strlen.de>
To: Cong Wang <xiyou.wangcong@gmail.com>
Cc: netdev@vger.kernel.org, bpf@vger.kernel.org,
Cong Wang <cong.wang@bytedance.com>,
syzbot+0c4150bff9fff3bf023c@syzkaller.appspotmail.com,
Florian Westphal <fw@strlen.de>
Subject: Re: [Patch net] net: remove the bogus overflow debug check in pskb_may_pull()
Date: Fri, 7 Jun 2024 01:27:47 +0200 [thread overview]
Message-ID: <20240606232747.GE9890@breakpoint.cc> (raw)
In-Reply-To: <20240606221531.255224-1-xiyou.wangcong@gmail.com>
Cong Wang <xiyou.wangcong@gmail.com> wrote:
> From: Cong Wang <cong.wang@bytedance.com>
>
> Commit 219eee9c0d16 ("net: skbuff: add overflow debug check to pull/push
> helpers") introduced an overflow debug check for pull/push helpers.
> For __skb_pull() this makes sense because its callers rarely check its
> return value. But for pskb_may_pull() it does not make sense, since its
> return value is properly taken care of. Remove the one in
> pskb_may_pull(), we can continue rely on its return value.
See 025f8ad20f2e3264d11683aa9cbbf0083eefbdcd which would not exist
without this check, I would not give up yet.
bpf_try_make_writable() could do an explicit check vs. skb->len.
If anyone needs it, splat is at
https://syzkaller.appspot.com/bug?extid=0c4150bff9fff3bf023c
next prev parent reply other threads:[~2024-06-06 23:27 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-06-06 22:15 [Patch net] net: remove the bogus overflow debug check in pskb_may_pull() Cong Wang
2024-06-06 23:27 ` Florian Westphal [this message]
2024-06-07 16:14 ` Cong Wang
2024-06-07 21:32 ` Kuniyuki Iwashima
2024-06-08 8:01 ` Eric Dumazet
2024-06-08 22:24 ` Florian Westphal
2024-06-09 2:01 ` Jason Xing
2024-06-14 10:17 ` [PATCH bpf] bpf: avoid splat in pskb_pull_reason Florian Westphal
2024-06-14 12:11 ` Eric Dumazet
2024-06-14 15:30 ` patchwork-bot+netdevbpf
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