linux-kernel - Re: Bug: slab-out-of-bounds Write in __bh

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Message-Id: <5757218E-52F8-49C7-95F1-9051EB51A2F3@m.fudan.edu.cn>
Date: Wed, 8 Jan 2025 12:08:56 +0800
From: Kun Hu <huk23@...udan.edu.cn>
To: Jan Kara <jack@...e.cz>
Cc: viro@...iv.linux.org.uk,
 brauner@...nel.org,
 linux-fsdevel@...r.kernel.org,
 linux-kernel@...r.kernel.org,
 "jjtan24@...udan.edu.cn" <jjtan24@...udan.edu.cn>
Subject: Re: Bug: slab-out-of-bounds Write in __bh_read


>> 
>> HEAD commit: fc033cf25e612e840e545f8d5ad2edd6ba613ed5
>> git tree: upstream
>> Console output: https://drive.google.com/file/d/1-YGytaKuh9M4hI6x27YjsE0vSyRFngf5/view?usp=sharing
>> Kernel config: https://drive.google.com/file/d/1n2sLNg-YcIgZqhhQqyMPTDWM_N1Pqz73/view?usp=sharing
>> C reproducer: /
>> Syzlang reproducer: /
>> 
>> We found an issue in the __bh_read function at line 3086, where a
>> slab-out-of-bounds error was reported. While the BUG_ON check ensures
>> that bh is locked, I suspect it’s possible that bh might have been
>> released prior to the call to __bh_read. This could result in accessing
>> invalid memory, ultimately triggering the reported issue.
> 
> Well, most likely the bh pointer has already been corrupted. Again, nobody
> is likely to be able to debug this unless we have a reliable way to
> reproduce this problem.


Hi, Jan.

We have obtained the reproducers of this issue for multi round testing. But, the crash location seems to vary. The crash log shows a possible deadlock occurring in “gfs2_trans_begin" in /fs/gfs2/trans.c, with duplicate registrations happening when attempting to register a "kobject."

The links of these related files are at below:

Log: https://drive.google.com/file/d/1MaRMA6WKz4e7fuDw-Yrb-Zw6GhXSIFsr/view?usp=sharing
C repro: https://drive.google.com/file/d/1VdDFjW2XNDhxe9yjb01qLblDxJpQyxzh/view?usp=sharing
Syz repro: https://drive.google.com/file/d/1sLGQnJb2-DCA6EsLia8SyOte0zKnlbF7/view?usp=sharing

———
Thanks,
Kun Hu