linux-kernel - Re: [PATCH net-next v5] ppp: Fix KMSAN uninit-value warning with bpf

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Message-Id: 
 <174113703200.354590.6042068788472875055.git-patchwork-notify@kernel.org>
Date: Wed, 05 Mar 2025 01:10:32 +0000
From: patchwork-bot+netdevbpf@...nel.org
To: Jiayuan Chen <jiayuan.chen@...ux.dev>
Cc: horms@...nel.org, kuba@...nel.org, bpf@...r.kernel.org,
 netdev@...r.kernel.org, andrew+netdev@...n.ch, davem@...emloft.net,
 edumazet@...gle.com, pabeni@...hat.com, ricardo@...liere.net,
 viro@...iv.linux.org.uk, dmantipov@...dex.ru, aleksander.lobakin@...el.com,
 linux-ppp@...r.kernel.org, linux-kernel@...r.kernel.org, mrpre@....com,
 paulus@...ba.org, syzbot+853242d9c9917165d791@...kaller.appspotmail.com
Subject: Re: [PATCH net-next v5] ppp: Fix KMSAN uninit-value warning with bpf

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@...nel.org>:

On Fri, 28 Feb 2025 22:14:08 +0800 you wrote:
> Syzbot caught an "KMSAN: uninit-value" warning [1], which is caused by the
> ppp driver not initializing a 2-byte header when using socket filter.
> 
> The following code can generate a PPP filter BPF program:
> '''
> struct bpf_program fp;
> pcap_t *handle;
> handle = pcap_open_dead(DLT_PPP_PPPD, 65535);
> pcap_compile(handle, &fp, "ip and outbound", 0, 0);
> bpf_dump(&fp, 1);
> '''
> Its output is:
> '''
> (000) ldh [2]
> (001) jeq #0x21 jt 2 jf 5
> (002) ldb [0]
> (003) jeq #0x1 jt 4 jf 5
> (004) ret #65535
> (005) ret #0
> '''
> Wen can find similar code at the following link:
> https://github.com/ppp-project/ppp/blob/master/pppd/options.c#L1680
> The maintainer of this code repository is also the original maintainer
> of the ppp driver.
> 
> [...]

Here is the summary with links:
  - [net-next,v5] ppp: Fix KMSAN uninit-value warning with bpf
    https://git.kernel.org/netdev/net/c/4c2d14c40a68

You are awesome, thank you!
-- 
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