2022-05-17 20:58:05

by Florian Westphal

[permalink] [raw]
Subject: Re: [syzbot] KASAN: use-after-free Read in nf_confirm

syzbot <[email protected]> wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: d887ae3247e0 octeontx2-pf: Remove unnecessary synchronize_..
> git tree: net-next
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=17f2b659f00000
> kernel config: https://syzkaller.appspot.com/x/.config?x=b1aab282dc5dd920
> dashboard link: https://syzkaller.appspot.com/bug?extid=793a590957d9c1b96620
> compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1313dce6f00000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=169eb59ef00000
>
> The issue was bisected to:
>
> commit 1397af5bfd7d32b0cf2adb70a78c9a9e8f11d912
> Author: Florian Westphal <[email protected]>
> Date: Mon Apr 11 11:01:18 2022 +0000
>
> netfilter: conntrack: remove the percpu dying list

AFAICS this bug exists since
Fixes: 71d8c47fc653 ("netfilter: conntrack: introduce clash resolution on insertion race")

nf_confirm needs to re-fetch 'ct' from skb->_nfct. Will send a patch.