From: Stefan Hajnoczi <stefanha@redhat.com>
To: virtualization@lists.linux-foundation.org
Cc: syzkaller-bugs@googlegroups.com, mst@redhat.com,
Linus Torvalds <torvalds@linux-foundation.org>,
kvm@vger.kernel.org, jasowang@redhat.com,
linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
Stefan Hajnoczi <stefanha@redhat.com>
Subject: [PATCH v2 1/2] vhost: fix vhost_vq_access_ok() log check
Date: Tue, 10 Apr 2018 13:26:29 +0800 [thread overview]
Message-ID: <20180410052630.11270-2-stefanha@redhat.com> (raw)
In-Reply-To: <20180410052630.11270-1-stefanha@redhat.com>
Commit d65026c6c62e7d9616c8ceb5a53b68bcdc050525 ("vhost: validate log
when IOTLB is enabled") introduced a regression. The logic was
originally:
if (vq->iotlb)
return 1;
return A && B;
After the patch the short-circuit logic for A was inverted:
if (A || vq->iotlb)
return A;
return B;
This patch fixes the regression by rewriting the checks in the obvious
way, no longer returning A when vq->iotlb is non-NULL (which is hard to
understand).
Reported-by: syzbot+65a84dde0214b0387ccd@syzkaller.appspotmail.com
Cc: Jason Wang <jasowang@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
---
drivers/vhost/vhost.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 5320039671b7..93fd0c75b0d8 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1244,10 +1244,12 @@ static int vq_log_access_ok(struct vhost_virtqueue *vq,
/* Caller should have vq mutex and device mutex */
int vhost_vq_access_ok(struct vhost_virtqueue *vq)
{
- int ret = vq_log_access_ok(vq, vq->log_base);
+ if (!vq_log_access_ok(vq, vq->log_base))
+ return 0;
- if (ret || vq->iotlb)
- return ret;
+ /* Access validation occurs at prefetch time with IOTLB */
+ if (vq->iotlb)
+ return 1;
return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used);
}
--
2.14.3
next prev parent reply other threads:[~2018-04-10 5:27 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 5:26 [PATCH v2 0/2] vhost: fix vhost_vq_access_ok() log check Stefan Hajnoczi
2018-04-10 5:26 ` Stefan Hajnoczi [this message]
2018-04-10 13:22 ` [PATCH v2 1/2] " Michael S. Tsirkin
2018-04-10 13:27 ` Michael S. Tsirkin
2018-04-10 5:26 ` [PATCH v2 2/2] vhost: return bool from *_access_ok() functions Stefan Hajnoczi
2018-04-10 13:29 ` Michael S. Tsirkin
2018-04-10 6:40 ` [PATCH v2 0/2] vhost: fix vhost_vq_access_ok() log check Jason Wang
2018-04-10 14:50 ` David Miller
2018-04-11 1:21 ` Stefan Hajnoczi
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