From: Björn Töpel <bjorn.topel@intel.com>
Date: Wed, 4 Sep 2019 11:49:10 +0000 (+0200)
Subject: xsk: avoid store-tearing when assigning queues
X-Git-Tag: v4.19.99~97
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c31ead3c88ed00e96ceb482587af224c72d72ee0;p=thirdparty%2Fkernel%2Fstable.git

xsk: avoid store-tearing when assigning queues

[ 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>
---

diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index c90854bc3048e..b580078f04d15 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;
 }