linux-kernel - Re: [PATCH net v3] net: atm: implement pre

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Message-ID: <tencent_4312D7064DC99FEEF62ED1CC8827F946E806@qq.com>
Date: Wed, 10 Dec 2025 18:50:02 +0800
From: Edward Adam Davis <eadavis@...com>
To: horms@...nel.org
Cc: davem@...emloft.net,
	eadavis@...com,
	edumazet@...gle.com,
	kuba@...nel.org,
	linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org,
	pabeni@...hat.com,
	syzbot+5dd615f890ddada54057@...kaller.appspotmail.com,
	syzkaller-bugs@...glegroups.com
Subject: Re: [PATCH net v3] net: atm: implement pre_send to check input before sending

Sun, Wed, 10 Dec 2025 10:31:34 +0000, Simon Horman wrote:
> > syzbot found an uninitialized targetless variable. The user-provided
> > data was only 28 bytes long, but initializing targetless requires at
> > least 44 bytes. This discrepancy ultimately led to the uninitialized
> > variable access issue reported by syzbot [1].
> >
> > Besides the issues reported by syzbot regarding targetless messages
> > [1], similar problems exist in other types of messages as well. We will
> > uniformly add input data checks to pre_send to prevent uninitialized
> > issues from recurring.
> >
> > Additionally, for cases where sizeoftlvs is greater than 0, the skb
> > requires more memory, and this will also be checked.
> >
> > [1]
> > BUG: KMSAN: uninit-value in lec_arp_update net/atm/lec.c:1845 [inline]
> >  lec_arp_update net/atm/lec.c:1845 [inline]
> >  lec_atm_send+0x2b02/0x55b0 net/atm/lec.c:385
> >  vcc_sendmsg+0x1052/0x1190 net/atm/common.c:650
> >
> > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > Reported-by: syzbot+5dd615f890ddada54057@...kaller.appspotmail.com
> > Closes: https://syzkaller.appspot.com/bug?extid=5dd615f890ddada54057
> > Signed-off-by: Edward Adam Davis <eadavis@...com>
> > ---
> > v3:
> >   - update coding style and practices
> > v2: https://lore.kernel.org/all/tencent_E83074AB763967783C9D36949674363C4A09@qq.com/
> >   - update subject and comments for pre_send
> > v1: https://lore.kernel.org/all/tencent_B31D1B432549BA28BB5633CB9E2C1B124B08@qq.com
> 
> FTR, a similar patch has been posted by Dharanitharan (CCed)
Didn't you check the dates? I released the third version of the patch
on December 4th (the first version was on November 28th), while this
person above released their first version of the patch on December 7th.
Their patch is far too similar to mine!