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Date: Mon, 29 Jan 2024 19:16:51 +0800
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Subject: Re: [f2fs-dev] [PATCH v1] f2fs: fix NULL pointer dereference in
 f2fs_submit_page_write()
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From: Chao Yu <chao@kernel.org>
To: Wenjie Qi <qwjhust@gmail.com>, jaegeuk@kernel.org
Cc: linux-kernel@vger.kernel.org, hustqwj@hust.edu.cn,
 linux-f2fs-devel@lists.sourceforge.net
References: <20240116141138.1245-1-qwjhust@gmail.com>
 <d379bc01-ca31-41e6-9d85-7fca846af491@kernel.org>
In-Reply-To: <d379bc01-ca31-41e6-9d85-7fca846af491@kernel.org>
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On 2024/1/29 18:27, Chao Yu wrote:
> On 2024/1/16 22:11, Wenjie Qi wrote:
>> BUG: kernel NULL pointer dereference, address: 0000000000000014
>> RIP: 0010:f2fs_submit_page_write+0x6cf/0x780 [f2fs]
>> Call Trace:
>> <TASK>
>> ? show_regs+0x6e/0x80
>> ? __die+0x29/0x70
>> ? page_fault_oops+0x154/0x4a0
>> ? prb_read_valid+0x20/0x30
>> ? __irq_work_queue_local+0x39/0xd0
>> ? irq_work_queue+0x36/0x70
>> ? do_user_addr_fault+0x314/0x6c0
>> ? exc_page_fault+0x7d/0x190
>> ? asm_exc_page_fault+0x2b/0x30
>> ? f2fs_submit_page_write+0x6cf/0x780 [f2fs]
>> ? f2fs_submit_page_write+0x736/0x780 [f2fs]
>> do_write_page+0x50/0x170 [f2fs]
>> f2fs_outplace_write_data+0x61/0xb0 [f2fs]
>> f2fs_do_write_data_page+0x3f8/0x660 [f2fs]
>> f2fs_write_single_data_page+0x5bb/0x7a0 [f2fs]
>> f2fs_write_cache_pages+0x3da/0xbe0 [f2fs]
>> ...
>> It is possible that other threads have added this fio to io->bio
>> and submitted the io->bio before entering f2fs_submit_page_write().
>> At this point io->bio = NULL.
>> If is_end_zone_blkaddr(sbi, fio->new_blkaddr) of this fio is true,
>> then an NULL pointer dereference error occurs at bio_get(io->bio).
>> The original code for determining zone end was after "out:",
>> which would have missed some fio who is zone end. I've moved
>>   this code before "skip:" to make sure it's done for each fio.
>>

Fixes: e067dc3c6b9c ("f2fs: maintain six open zones for zoned devices")

>> Signed-off-by: Wenjie Qi <qwjhust@gmail.com>
> 
> Reviewed-by: Chao Yu <chao@kernel.org>
> 
> Thanks,
> 
> 
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