From: Kuniyuki Iwashima <kuniyu@amazon.com>
To: <xiyou.wangcong@gmail.com>
Cc: <bpf@vger.kernel.org>, <cong.wang@bytedance.com>, <fw@strlen.de>,
<netdev@vger.kernel.org>,
<syzbot+0c4150bff9fff3bf023c@syzkaller.appspotmail.com>,
<kuniyu@amazon.com>
Subject: Re: [Patch net] net: remove the bogus overflow debug check in pskb_may_pull()
Date: Fri, 7 Jun 2024 14:32:29 -0700 [thread overview]
Message-ID: <20240607213229.97602-1-kuniyu@amazon.com> (raw)
In-Reply-To: <ZmMxzPoDTNu06itR@pop-os.localdomain>
From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 7 Jun 2024 09:14:04 -0700
> On Fri, Jun 07, 2024 at 01:27:47AM +0200, Florian Westphal wrote:
> > 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.
>
> What's the point of that commit?
4b911a9690d7 would be better example. The warning actually found a
bug in NSH GSO.
Here's splats triggered by syzkaller using NSH over various tunnels.
https://lore.kernel.org/netdev/20240415222041.18537-2-kuniyu@amazon.com/
next prev parent reply other threads:[~2024-06-07 21:32 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
2024-06-07 16:14 ` Cong Wang
2024-06-07 21:32 ` Kuniyuki Iwashima [this message]
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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