netdev - Re: [PATCH bpf] bpf, test_run: Fix use-after-free issue in eth_skb_pkt

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Message-Id: <20241202.215609.382397812745347709.syoshida@redhat.com>
Date: Mon, 02 Dec 2024 21:56:09 +0900 (JST)
From: Shigeru Yoshida <syoshida@...hat.com>
To: glider@...gle.com
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org,
 martin.lau@...ux.dev, eddyz87@...il.com, song@...nel.org,
 yonghong.song@...ux.dev, john.fastabend@...il.com, kpsingh@...nel.org,
 sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com, horms@...nel.org,
 hawk@...nel.org, lorenzo@...nel.org, toke@...hat.com, bpf@...r.kernel.org,
 netdev@...r.kernel.org, syzkaller@...glegroups.com
Subject: Re: [PATCH bpf] bpf, test_run: Fix use-after-free issue in
 eth_skb_pkt_type()

On Mon, 2 Dec 2024 10:32:04 +0100, Alexander Potapenko wrote:
> On Sun, Dec 1, 2024 at 4:27 PM Shigeru Yoshida <syoshida@...hat.com> wrote:
>>
>> KMSAN reported a use-after-free issue in eth_skb_pkt_type()[1]. The
>> cause of the issue was that eth_skb_pkt_type() accessed skb's data
>> that didn't contain an Ethernet header. This occurs when
>> bpf_prog_test_run_xdp() passes an invalid value as the user_data
>> argument to bpf_test_init().
> 
> Hi Shigeru,
> 
> Thanks for taking care of this!
> 
> Am I understanding right that this bug was reported by your own
> syzkaller instance?

Hi Alexander,

Thank you for your comment!

Yes, this issue was identified by running my own syzkaller locally.

I added the "Reported-by: syzkaller <syzkaller@...glegroups.com>" tag
to give credit to the syzkaller community.

> Otherwise, if the report originates from syzkaller.appspot.com, could
> you please append the bug hash to the Reported-by: tag?

I checked syzkaller.appspot.com, but this issue does not seem to be
reported.

Thanks,  
Shigeru