[PATCH bpf-next 3/4] xsk: avoid store-tearing when assigning umem

[Björn Töpel]

From: Björn Töpel <bjorn.to...@intel.com>

The umem member of struct xdp_sock is read outside of the control
mutex, in the mmap implementation, and needs a WRITE_ONCE to avoid
potentional store-tearing.

Fixes: 423f38329d26 ("xsk: add umem fill queue support and mmap")
Signed-off-by: Björn Töpel <bjorn.to...@intel.com>
---
 net/xdp/xsk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 31236e61069b..6dde1857ed52 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -718,7 +718,7 @@ static int xsk_setsockopt(struct socket *sock, int level, 
int optname,
 
                /* Make sure umem is ready before it can be seen by others */
                smp_wmb();
-               xs->umem = umem;
+               WRITE_ONCE(xs->umem, umem);
                mutex_unlock(&xs->mutex);
                return 0;
        }
-- 
2.20.1