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From: Chao Yu <chao@kernel.org>
To: Hoi Pok Wu <wuhoipok@gmail.com>, jaegeuk@kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org,
	syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] fs: f2fs: fix kernel discard_thread NULL dereference
Date: Mon, 17 Oct 2022 20:23:51 +0800	[thread overview]
Message-ID: <39c430b1-f4f1-e0a7-1089-9db85d1163d9@kernel.org> (raw)
In-Reply-To: <20221017100437.618363-1-wuhoipok@gmail.com>

On 2022/10/17 18:04, Hoi Pok Wu wrote:
> Pointer discard_thread is pointing to nowhere, using IS_ERR prevents the
> situation. IS_ERR also seen being used throughout the file.

I guess below patch can fix this issue from root cause?

https://lore.kernel.org/linux-f2fs-devel/20221013155628.434671-1-chao@kernel.org/T/#u

Thanks,

> 
> Link: https://syzkaller.appspot.com/bug?id=9499bc6574cea5940e48199c2fd0732d9b11e5e1
> Reported-by: syzbot+035a381ea1afb63f098d@syzkaller.appspotmail.com
> Signed-off-by: Hoi Pok Wu <wuhoipok@gmail.com>
> ---
>   fs/f2fs/segment.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index acf3d3fa4363..79978b7206b5 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -1634,7 +1634,8 @@ void f2fs_stop_discard_thread(struct f2fs_sb_info *sbi)
>   		struct task_struct *discard_thread = dcc->f2fs_issue_discard;
>   
>   		dcc->f2fs_issue_discard = NULL;
> -		kthread_stop(discard_thread);
> +		if (!IS_ERR(discard_thread))
> +			kthread_stop(discard_thread);
>   	}
>   }
>   

      reply	other threads:[~2022-10-17 12:24 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-17 10:04 Hoi Pok Wu
2022-10-17 12:23 ` Chao Yu [this message]

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