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From: Tong Zhang <ztong0001@gmail.com>
To: Keith Busch <kbusch@kernel.org>
Cc: Jens Axboe <axboe@fb.com>, Christoph Hellwig <hch@lst.de>,
	Sagi Grimberg <sagi@grimberg.me>,
	linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] nvme: fix NULL pointer dereference
Date: Thu, 17 Sep 2020 23:32:12 -0400	[thread overview]
Message-ID: <CAA5qM4ADbaO25t7GzC7jqB_jamHgegUyuNMvpo5h1+h=rir2mA@mail.gmail.com> (raw)
In-Reply-To: <CAA5qM4Bj3BqYt-J=YqWKMWLFxDaMwQa4qAqPibyikpX5FBSzRQ@mail.gmail.com>

Please correct me if I am wrong.
After a bit more digging I found out that it is indeed command_id got
corrupted is causing this problem. Although the tag and command_id
range is checked like you said, the elements in rqs cannot be
guaranteed to be not NULL. thus although the range check is passed,
blk_mq_tag_to_rq() can still return NULL. It is clear that the current
sanitization is not enough and there's more implication about this --
when all rqs got populated, a corrupted command_id may silently
corrupt other data not belonging to the current command.

- Tong

On Thu, Sep 17, 2020 at 8:44 PM Tong Zhang <ztong0001@gmail.com> wrote:
>
> Hmm..Yeah.. I see your point.
> I was naivly thinking the command_id was the culprit.
>
> On Thu, Sep 17, 2020 at 1:14 PM Keith Busch <kbusch@kernel.org> wrote:
> >
> > On Thu, Sep 17, 2020 at 12:56:59PM -0400, Tong Zhang wrote:
> > > The command_id in CQE is writable by NVMe controller, driver should
> > > check its sanity before using it.
> >
> > We already do that.

WARNING: multiple messages have this Message-ID (diff)
From: Tong Zhang <ztong0001@gmail.com>
To: Keith Busch <kbusch@kernel.org>
Cc: Jens Axboe <axboe@fb.com>,
	linux-kernel@vger.kernel.org, Christoph Hellwig <hch@lst.de>,
	linux-nvme@lists.infradead.org, Sagi Grimberg <sagi@grimberg.me>
Subject: Re: [PATCH] nvme: fix NULL pointer dereference
Date: Thu, 17 Sep 2020 23:32:12 -0400	[thread overview]
Message-ID: <CAA5qM4ADbaO25t7GzC7jqB_jamHgegUyuNMvpo5h1+h=rir2mA@mail.gmail.com> (raw)
In-Reply-To: <CAA5qM4Bj3BqYt-J=YqWKMWLFxDaMwQa4qAqPibyikpX5FBSzRQ@mail.gmail.com>

Please correct me if I am wrong.
After a bit more digging I found out that it is indeed command_id got
corrupted is causing this problem. Although the tag and command_id
range is checked like you said, the elements in rqs cannot be
guaranteed to be not NULL. thus although the range check is passed,
blk_mq_tag_to_rq() can still return NULL. It is clear that the current
sanitization is not enough and there's more implication about this --
when all rqs got populated, a corrupted command_id may silently
corrupt other data not belonging to the current command.

- Tong

On Thu, Sep 17, 2020 at 8:44 PM Tong Zhang <ztong0001@gmail.com> wrote:
>
> Hmm..Yeah.. I see your point.
> I was naivly thinking the command_id was the culprit.
>
> On Thu, Sep 17, 2020 at 1:14 PM Keith Busch <kbusch@kernel.org> wrote:
> >
> > On Thu, Sep 17, 2020 at 12:56:59PM -0400, Tong Zhang wrote:
> > > The command_id in CQE is writable by NVMe controller, driver should
> > > check its sanity before using it.
> >
> > We already do that.

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

  reply	other threads:[~2020-09-18  3:32 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-16 15:36 [PATCH] nvme: fix NULL pointer dereference Tong Zhang
2020-09-16 15:36 ` Tong Zhang
2020-09-16 16:54 ` Keith Busch
2020-09-16 16:54   ` Keith Busch
2020-09-17 16:56   ` Tong Zhang
2020-09-17 16:56     ` Tong Zhang
2020-09-17 17:14     ` Keith Busch
2020-09-17 17:14       ` Keith Busch
2020-09-18  0:44       ` Tong Zhang
2020-09-18  0:44         ` Tong Zhang
2020-09-18  3:32         ` Tong Zhang [this message]
2020-09-18  3:32           ` Tong Zhang
2020-09-18 18:38           ` Keith Busch
2020-09-18 18:38             ` Keith Busch

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