linux-kernel - Re: [PATCH v2] f2fs: fix to do sanity check for inline inode

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Date:   Sun, 15 May 2022 16:57:19 +0800
From:   Chao Yu <chao@...nel.org>
To:     Bagas Sanjaya <bagasdotme@...il.com>
Cc:     jaegeuk@...nel.org, linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Ming Yan <yanming@....edu.cn>, Chao Yu <chao.yu@...o.com>
Subject: Re: [PATCH v2] f2fs: fix to do sanity check for inline inode

On 2022/5/14 20:14, Bagas Sanjaya wrote:
> On Sat, May 14, 2022 at 04:01:02PM +0800, Chao Yu wrote:
>> As Yanming reported in bugzilla:
>>
>> https://bugzilla.kernel.org/show_bug.cgi?id=215895
>>
>> I have encountered a bug in F2FS file system in kernel v5.17.
>>
>> The kernel message is shown below:
>>
>> kernel BUG at fs/inode.c:611!
>> Call Trace:
>>   evict+0x282/0x4e0
>>   __dentry_kill+0x2b2/0x4d0
>>   dput+0x2dd/0x720
>>   do_renameat2+0x596/0x970
>>   __x64_sys_rename+0x78/0x90
>>   do_syscall_64+0x3b/0x90
>>
>> The root cause is: fuzzed inode has both inline_data flag and encrypted
>> flag, so after it was deleted by rename(), during f2fs_evict_inode(),
>> it will cause inline data conversion due to flags confilction, then
>> page cache will be polluted and trigger panic in clear_inode().
>>
>> This patch tries to fix the issue by do more sanity checks for inline
>> data inode in sanity_check_inode().
>>
>> Cc: stable@...r.kernel.org
>> Reported-by: Ming Yan <yanming@....edu.cn>
>> Signed-off-by: Chao Yu <chao.yu@...o.com>
> 
> Hi Chao,
> 
> I think the patch message can be reworked , like below:

Hi Bagas,

Thanks a lot for your cleanup. :)

> 
> Yanming reported a kernel bug in Bugzilla kernel, which can be reproduced.
> The bug message is:

I will keep the link for backtrace.

> 
> kernel BUG at fs/inode.c:611!
> Call Trace:
>   evict+0x282/0x4e0
>   __dentry_kill+0x2b2/0x4d0
>   dput+0x2dd/0x720
>   do_renameat2+0x596/0x970
>   __x64_sys_rename+0x78/0x90
>   do_syscall_64+0x3b/0x90
> 
> The bug is due to fuzzed inode has both inline_data and encrypted flags.
> During f2fs_evict_inode(), after the inode was deleted by rename(), it

I prefer "during f2fs_evict_inode(), as inode was deleted by rename()"

> will cause inline data conversion due to conflicting flags. The page
> cache will be polluted and the panic will be triggered in clear_inode().
> 
> Try fixing the bug by doing more sanity checks for inline data inode in
> sanity_check_inode().

Let me revise in v3.

Thanks,

> 
> Thanks.
>