lkml.org 
[lkml]   [2018]   [Dec]   [10]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH net 1/4] vhost: make sure used idx is seen before log in vhost_add_used_n()
    Date
    We miss a write barrier that guarantees used idx is updated and seen
    before log. This will let userspace sync and copy used ring before
    used idx is update. Fix this by adding a barrier before log_write().

    Fixes: 8dd014adfea6f ("vhost-net: mergeable buffers support")
    Signed-off-by: Jason Wang <jasowang@redhat.com>
    ---
    drivers/vhost/vhost.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
    index 6b98d8e3a5bf..5915f240275a 100644
    --- a/drivers/vhost/vhost.c
    +++ b/drivers/vhost/vhost.c
    @@ -2220,6 +2220,8 @@ int vhost_add_used_n(struct vhost_virtqueue *vq, struct vring_used_elem *heads,
    return -EFAULT;
    }
    if (unlikely(vq->log_used)) {
    + /* Make sure used idx is seen before log. */
    + smp_wmb();
    /* Log used index update. */
    log_write(vq->log_base,
    vq->log_addr + offsetof(struct vring_used, idx),
    --
    2.17.1
    \
     
     \ /
      Last update: 2018-12-10 10:46    [W:2.579 / U:0.448 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site