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[192.55.54.39]) by smtp.gmail.com with ESMTPSA id b126sm48257008pfa.177.2019.09.04.04.49.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Sep 2019 04:49:35 -0700 (PDT) From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= To: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org Cc: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , magnus.karlsson@intel.com, magnus.karlsson@gmail.com, bpf@vger.kernel.org, jonathan.lemon@gmail.com, syzbot+c82697e3043781e08802@syzkaller.appspotmail.com, hdanton@sina.com, i.maximets@samsung.com Subject: [PATCH bpf-next v3 2/4] xsk: avoid store-tearing when assigning umem Date: Wed, 4 Sep 2019 13:49:11 +0200 Message-Id: <20190904114913.17217-3-bjorn.topel@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190904114913.17217-1-bjorn.topel@gmail.com> References: <20190904114913.17217-1-bjorn.topel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org From: Björn Töpel 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 --- 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 271d8d3fb11e..8c9056f06989 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -644,7 +644,7 @@ 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; @@ -751,7 +751,7 @@ 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