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Date: Mon, 4 Mar 2024 09:40:35 -0800
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Subject: Re: [PATCH] fs/aio: fix uaf in sys_io_cancel
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To: Benjamin LaHaise <ben@communityfibre.ca>
Cc: Edward Adam Davis <eadavis@qq.com>,
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From: Bart Van Assche <bvanassche@acm.org>
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On 3/4/24 09:31, Benjamin LaHaise wrote:
> A revert is justified when a series of patches is buggy and had
> insufficient review prior to merging.

That's not how Linux kernel development works. If a bug can get fixed
easily, a fix is preferred instead of reverting + reapplying a patch.

> Using the "a kernel warning hit" approach for work on cancellation is
> very much a sign that the patches were half baked.
Is there perhaps a misunderstanding? My patches fix a kernel warning and
did not introduce any new WARN*() statements.

> Why are you touching the kiocb after ownership has already been
> passed on to another entity?
Touching the kiocb after ownership has been passed is the result of an
oversight. Whether or not kiocb->ki_cancel() transfers ownership depends
on the I/O type. The use-after-free was not introduced on purpose.

Bart.