linux-kernel - Re: [syzbot] [usb?] [media?] KASAN: use-after-free Read in em28xx_init

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Message-ID: <ab7652b5-f854-4221-99a3-1c5b192b29ff@rowland.harvard.edu>
Date: Tue, 13 May 2025 11:11:15 -0400
From: Alan Stern <stern@...land.harvard.edu>
To: syzbot <syzbot+99d6c66dbbc484f50e1c@...kaller.appspotmail.com>
Cc: gregkh@...uxfoundation.org, hdanton@...a.com,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	linux-usb@...r.kernel.org, mchehab@...nel.org, paskripkin@...il.com,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [usb?] [media?] KASAN: use-after-free Read in
 em28xx_init_extension (2)

On Tue, May 13, 2025 at 08:02:01AM -0700, syzbot wrote:
> syzbot has bisected this issue to:
> 
> commit a368ecde8a5055b627749b09c6218ef793043e47
> Author: Alan Stern <stern@...land.harvard.edu>
> Date:   Thu Jun 27 19:56:18 2024 +0000
> 
>     USB: core: Fix duplicate endpoint bug by clearing reserved bits in the descriptor
> 
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=12cf6cd4580000
> start commit:   cd802e7e5f1e Merge tag 'for-linus' of git://git.kernel.org..
> git tree:       upstream
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=11cf6cd4580000
> console output: https://syzkaller.appspot.com/x/log.txt?x=16cf6cd4580000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=91c351a0f6229e67
> dashboard link: https://syzkaller.appspot.com/bug?extid=99d6c66dbbc484f50e1c
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=143a7768580000
> 
> Reported-by: syzbot+99d6c66dbbc484f50e1c@...kaller.appspotmail.com
> Fixes: a368ecde8a50 ("USB: core: Fix duplicate endpoint bug by clearing reserved bits in the descriptor")
> 
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

Clearly a ridiculous claim.  Maybe the bug fixed by that commit covered 
up the actual cause of this problem.

Alan Stern