From: Stefan Hajnoczi <stefanha@redhat.com>
To: Greg Kurz <groug@kaod.org>
Cc: "Daniel P . Berrangé" <berrange@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org,
"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
virtio-fs@redhat.com, "Vivek Goyal" <vgoyal@redhat.com>
Subject: Re: [PATCH v2 2/7] vhost-user: Fix double-close on slave_read() error path
Date: Mon, 15 Mar 2021 10:36:10 +0000 [thread overview]
Message-ID: <YE84mp9zLcGthhDg@stefanha-x1.localdomain> (raw)
In-Reply-To: <20210312092212.782255-3-groug@kaod.org>
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On Fri, Mar 12, 2021 at 10:22:07AM +0100, Greg Kurz wrote:
> Some message types, e.g. VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG,
> can convey file descriptors. These must be closed before returning
> from slave_read() to avoid being leaked. This can currently be done
> in two different places:
>
> [1] just after the request has been processed
>
> [2] on the error path, under the goto label err:
>
> These path are supposed to be mutually exclusive but they are not
> actually. If the VHOST_USER_NEED_REPLY_MASK flag was passed and the
> sending of the reply fails, both [1] and [2] are performed with the
> same descriptor values. This can potentially cause subtle bugs if one
> of the descriptor was recycled by some other thread in the meantime.
>
> This code duplication complicates rollback for no real good benefit.
> Do the closing in a unique place, under a new fdcleanup: goto label
> at the end of the function.
>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
> hw/virtio/vhost-user.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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WARNING: multiple messages have this Message-ID (diff)
From: Stefan Hajnoczi <stefanha@redhat.com>
To: Greg Kurz <groug@kaod.org>
Cc: "Daniel P . Berrangé" <berrange@redhat.com>,
"Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, virtio-fs@redhat.com,
"Vivek Goyal" <vgoyal@redhat.com>
Subject: Re: [Virtio-fs] [PATCH v2 2/7] vhost-user: Fix double-close on slave_read() error path
Date: Mon, 15 Mar 2021 10:36:10 +0000 [thread overview]
Message-ID: <YE84mp9zLcGthhDg@stefanha-x1.localdomain> (raw)
In-Reply-To: <20210312092212.782255-3-groug@kaod.org>
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On Fri, Mar 12, 2021 at 10:22:07AM +0100, Greg Kurz wrote:
> Some message types, e.g. VHOST_USER_SLAVE_VRING_HOST_NOTIFIER_MSG,
> can convey file descriptors. These must be closed before returning
> from slave_read() to avoid being leaked. This can currently be done
> in two different places:
>
> [1] just after the request has been processed
>
> [2] on the error path, under the goto label err:
>
> These path are supposed to be mutually exclusive but they are not
> actually. If the VHOST_USER_NEED_REPLY_MASK flag was passed and the
> sending of the reply fails, both [1] and [2] are performed with the
> same descriptor values. This can potentially cause subtle bugs if one
> of the descriptor was recycled by some other thread in the meantime.
>
> This code duplication complicates rollback for no real good benefit.
> Do the closing in a unique place, under a new fdcleanup: goto label
> at the end of the function.
>
> Signed-off-by: Greg Kurz <groug@kaod.org>
> ---
> hw/virtio/vhost-user.c | 11 +++--------
> 1 file changed, 3 insertions(+), 8 deletions(-)
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
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next prev parent reply other threads:[~2021-03-15 10:38 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 9:22 [PATCH v2 0/7] virtiofsd: Avoid potential deadlocks Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-12 9:22 ` [PATCH v2 1/7] vhost-user: Drop misleading EAGAIN checks in slave_read() Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 10:34 ` Stefan Hajnoczi
2021-03-15 10:34 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 2/7] vhost-user: Fix double-close on slave_read() error path Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 10:36 ` Stefan Hajnoczi [this message]
2021-03-15 10:36 ` Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 3/7] vhost-user: Factor out duplicated slave_fd teardown code Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 10:36 ` Stefan Hajnoczi
2021-03-15 10:36 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 4/7] vhost-user: Convert slave channel to QIOChannelSocket Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 10:37 ` Stefan Hajnoczi
2021-03-15 10:37 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 5/7] vhost-user: Introduce nested event loop in vhost_user_read() Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 10:38 ` Stefan Hajnoczi
2021-03-15 10:38 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 6/7] vhost-user: Monitor slave channel " Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 12:20 ` Stefan Hajnoczi
2021-03-15 12:20 ` [Virtio-fs] " Stefan Hajnoczi
2021-03-12 9:22 ` [PATCH v2 7/7] virtiofsd: Release vu_dispatch_lock when stopping queue Greg Kurz
2021-03-12 9:22 ` [Virtio-fs] " Greg Kurz
2021-03-15 14:57 ` Dr. David Alan Gilbert
2021-03-15 14:57 ` [Virtio-fs] " Dr. David Alan Gilbert
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