linux-kernel - Re: [PATCH v1] f2fs: fix NULL pointer dereference in f2fs_submit_page

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Date: Mon, 29 Jan 2024 18:27:39 +0800
From: Chao Yu <chao@...nel.org>
To: Wenjie Qi <qwjhust@...il.com>, jaegeuk@...nel.org
Cc: hustqwj@...t.edu.cn, linux-f2fs-devel@...ts.sourceforge.net,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] f2fs: fix NULL pointer dereference in
 f2fs_submit_page_write()

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.
> 
> Signed-off-by: Wenjie Qi <qwjhust@...il.com>

Reviewed-by: Chao Yu <chao@...nel.org>

Thanks,