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authorStefan Hajnoczi <stefanha@redhat.com>2018-04-11 10:35:40 +0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-04-20 08:21:07 +0200
commit72de9891b5f46f1f98e7e6243c47076a4b4daa3c (patch)
tree944d69bf0d90dac23b95690f69ff34e4e64336a3
parent0eecffb5e95390e72c5ac0c6d184881c14ad1b3a (diff)
vhost: fix vhost_vq_access_ok() log check
[ Upstream commit d14d2b78090c7de0557362b26a4ca591aa6a9faa ] 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> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/vhost/vhost.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index e2c37aeed45a..fce49ebc575d 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -1175,10 +1175,12 @@ 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);
}