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UPSTREAM: vhost: fix error path in vhost_init_used()

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We don't want side effects. If something fails, we rollback vq->is_le to
its previous value.

Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
(cherry picked from commit e1f33be918)
Bug: 121166534
Test: Ran cuttlefish with android-4.4 + VSOCKETS, VMWARE_VMCI_VSOCKETS
Signed-off-by: Alistair Strachan <astrachan@google.com>

Change-Id: I18c57e5c78aa3e89d267213770f915a5a5c76100
This commit is contained in:
Greg Kurz
2016-02-16 15:54:28 +01:00
committed by Alistair Strachan
parent c7c7d1506c
commit 6ef11fba4c
1 changed files with 11 additions and 4 deletions
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15
drivers/vhost/vhost.c
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@@ -1157,6 +1157,8 @@ int vhost_init_used(struct vhost_virtqueue *vq)
{
__virtio16 last_used_idx;
int r;
bool is_le = vq->is_le;
if (!vq->private_data) {
vq->is_le = virtio_legacy_is_little_endian();
return 0;
@@ -1166,15 +1168,20 @@ int vhost_init_used(struct vhost_virtqueue *vq)
r = vhost_update_used_flags(vq);
if (r)
return r;
goto err;
vq->signalled_used_valid = false;
if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx))
return -EFAULT;
if (!access_ok(VERIFY_READ, &vq->used->idx, sizeof vq->used->idx)) {
r = -EFAULT;
goto err;
}
r = __get_user(last_used_idx, &vq->used->idx);
if (r)
return r;
goto err;
vq->last_used_idx = vhost16_to_cpu(vq, last_used_idx);
return 0;
err:
vq->is_le = is_le;
return r;
}
EXPORT_SYMBOL_GPL(vhost_init_used);