From: Jan Beulich <jbeulich@suse.com>
To: Juergen Gross <jgross@suse.com>
Cc: "Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
"Stefano Stabellini" <sstabellini@kernel.org>,
"Konrad Rzeszutek Wilk" <konrad.wilk@oracle.com>,
"Roger Pau Monné" <roger.pau@citrix.com>,
"Jens Axboe" <axboe@kernel.dk>,
xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org,
linux-block@vger.kernel.org
Subject: Re: [PATCH 3/8] xen/blkfront: don't take local copy of a request from the ring page
Date: Mon, 17 May 2021 16:01:00 +0200 [thread overview]
Message-ID: <4cbf7b7f-5f00-4aba-4d54-06aa73d1bc32@suse.com> (raw)
In-Reply-To: <20210513100302.22027-4-jgross@suse.com>
On 13.05.2021 12:02, Juergen Gross wrote:
> In order to avoid a malicious backend being able to influence the local
> copy of a request build the request locally first and then copy it to
> the ring page instead of doing it the other way round as today.
>
> Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
with one remark/question:
> @@ -703,6 +704,7 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
> {
> struct blkfront_info *info = rinfo->dev_info;
> struct blkif_request *ring_req, *extra_ring_req = NULL;
> + struct blkif_request *final_ring_req, *final_extra_ring_req;
Without setting final_extra_ring_req to NULL just like is done for
extra_ring_req, ...
> @@ -840,10 +845,10 @@ static int blkif_queue_rw_req(struct request *req, struct blkfront_ring_info *ri
> if (setup.segments)
> kunmap_atomic(setup.segments);
>
> - /* Keep a private copy so we can reissue requests when recovering. */
> - rinfo->shadow[id].req = *ring_req;
> + /* Copy request(s) to the ring page. */
> + *final_ring_req = *ring_req;
> if (unlikely(require_extra_req))
> - rinfo->shadow[extra_id].req = *extra_ring_req;
> + *final_extra_ring_req = *extra_ring_req;
... are you sure all supported compilers will recognize the
conditional use and not warn about use of a possibly uninitialized
variable?
Jan
next prev parent reply other threads:[~2021-05-17 14:01 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-13 10:02 [PATCH 0/8] xen: harden frontends against malicious backends Juergen Gross
2021-05-13 10:02 ` [PATCH 1/8] xen: sync include/xen/interface/io/ring.h with Xen's newest version Juergen Gross
2021-05-13 10:02 ` [PATCH 2/8] xen/blkfront: read response from backend only once Juergen Gross
2021-05-17 13:50 ` Jan Beulich
2021-05-13 10:02 ` [PATCH 3/8] xen/blkfront: don't take local copy of a request from the ring page Juergen Gross
2021-05-17 14:01 ` Jan Beulich [this message]
2021-05-17 14:11 ` Juergen Gross
2021-05-13 10:02 ` [PATCH 4/8] xen/blkfront: don't trust the backend response data blindly Juergen Gross
2021-05-17 14:11 ` Jan Beulich
2021-05-17 14:23 ` Juergen Gross
2021-05-17 15:12 ` Jan Beulich
2021-05-17 15:22 ` Juergen Gross
2021-05-17 15:33 ` Jan Beulich
2021-07-08 5:47 ` Juergen Gross
2021-07-08 6:37 ` Jan Beulich
2021-07-08 6:40 ` Juergen Gross
2021-07-08 6:52 ` Jan Beulich
2021-07-08 6:56 ` Juergen Gross
2021-05-13 10:02 ` [PATCH 5/8] xen/netfront: read response from backend only once Juergen Gross
2021-05-17 14:20 ` Jan Beulich
2021-05-17 14:24 ` Juergen Gross
2021-05-13 10:03 ` [PATCH 6/8] xen/netfront: don't read data from request on the ring page Juergen Gross
2021-05-17 15:08 ` Jan Beulich
2021-05-13 10:03 ` [PATCH 7/8] xen/netfront: don't trust the backend response data blindly Juergen Gross
2021-05-17 15:31 ` Jan Beulich
2021-05-13 10:03 ` [PATCH 8/8] xen/hvc: replace BUG_ON() with negative return value Juergen Gross
2021-05-13 10:16 ` Christophe Leroy
2021-05-13 10:20 ` Juergen Gross
2021-05-13 10:25 ` Greg Kroah-Hartman
2021-05-13 10:35 ` Juergen Gross
2021-05-21 10:43 ` [PATCH 0/8] xen: harden frontends against malicious backends Marek Marczykowski-Górecki
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