From ad5f154c44cb8cf451c87e70095a9ddfb257141f Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Tue, 22 Sep 2020 10:12:28 +0800 Subject: [PATCH] xsk: avoid store-tearing when assigning umem MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit stable inclusion from linux-4.19.99 commit 43a807541949a4bc5fba0eb8b76af453b68ec3f0 -------------------------------- [ Upstream commit 9764f4b301c3e7eb3b75eec85b73cad449cdbb0d ] 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 potential store-tearing. Acked-by: Jonathan Lemon Fixes: 423f38329d26 ("xsk: add umem fill queue support and mmap") Signed-off-by: Björn Töpel Signed-off-by: Daniel Borkmann Signed-off-by: Sasha Levin Signed-off-by: Yang Yingliang Signed-off-by: Li Aichun Reviewed-by: guodeqing Signed-off-by: Yang Yingliang --- net/xdp/xsk.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index b580078f04d1..72caa4fb13f4 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -454,7 +454,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len) } xdp_get_umem(umem_xs->umem); - xs->umem = umem_xs->umem; + WRITE_ONCE(xs->umem, umem_xs->umem); sockfd_put(sock); } else if (!xs->umem || !xdp_umem_validate_queues(xs->umem)) { err = -EINVAL; @@ -534,7 +534,7 @@ 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; } -- GitLab