[PATCH AUTOSEL 4.19 529/671] xsk: avoid store-tearing when assigning queues

Sasha Levin
2020-01-16T18:42:43Z

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

[ Upstream commit 94a997637c5b562fa0ca44fca1d2cd02ec08236f ]

Use WRITE_ONCE when doing the store of tx, rx, fq, and cq, to avoid
potential store-tearing. These members are read outside of the control
mutex in the mmap implementation.

Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com>
Fixes: 37b076933a8e ("xsk: add missing write- and data-dependency barrier")
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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 c90854bc3048..b580078f04d1 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -320,7 +320,7 @@ static int xsk_init_queue(u32 entries, struct xsk_queue **queue,

/* Make sure queue is ready before it can be seen by others */
smp_wmb();
- *queue = q;
+ WRITE_ONCE(*queue, q);
return 0;
}

--
2.20.1