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From: Christoph Hellwig <hch@lst.de>
To: syzbot <syzbot+c27475eb921c46bbdc62@syzkaller.appspotmail.com>
Cc: akpm@linux-foundation.org, hch@lst.de, jack@suse.com,
	jack@suse.cz, linkinjeon@gmail.com,
	linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-mm@kvack.org, syzkaller-bugs@googlegroups.com,
	willy@infradead.org
Subject: Re: [syzbot] [udf?] BUG: unable to handle kernel NULL pointer dereference in __writepage
Date: Mon, 23 Jan 2023 08:36:09 +0100	[thread overview]
Message-ID: <20230123073609.GA31134@lst.de> (raw)
In-Reply-To: <0000000000009cfc1705f2a07641@google.com>

I looked into this and got really confused.  We should never end
up in generic_writepages if ->writepages is set, which this patch
obviously does.

Then I took a closer look at udf, and it seems to switch a_aops around
at run time, and it seems like we're hitting just that case, and the
patch just seems to narrow down that window.

I suspect the right fix is to remove this runtime switching of aops,
and just do conditionals inside the methods.

  reply	other threads:[~2023-01-23  7:36 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-12-17 15:04 [syzbot] [udf?] BUG: unable to handle kernel NULL pointer dereference in __writepage syzbot
2023-01-19 16:31 ` syzbot
2023-01-23  7:36   ` Christoph Hellwig [this message]
2023-01-23 17:18     ` Jan Kara

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