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Miller" , Sasha Levin Subject: [PATCH 5.3 093/197] rxrpc: use rcu protection while reading sk->sk_user_data Date: Sun, 27 Oct 2019 22:00:11 +0100 Message-Id: <20191027203356.781169462@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191027203351.684916567@linuxfoundation.org> References: <20191027203351.684916567@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 2ca4f6ca4562594ef161e4140c2a5e0e5282967b ] We need to extend the rcu_read_lock() section in rxrpc_error_report() and use rcu_dereference_sk_user_data() instead of plain access to sk->sk_user_data to make sure all rules are respected. The compiler wont reload sk->sk_user_data at will, and RCU rules prevent memory beeing freed too soon. Fixes: f0308fb07080 ("rxrpc: Fix possible NULL pointer access in ICMP handling") Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both") Signed-off-by: Eric Dumazet Cc: David Howells Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/rxrpc/peer_event.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index 61451281d74a3..48f67a9b1037c 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -147,13 +147,16 @@ void rxrpc_error_report(struct sock *sk) { struct sock_exterr_skb *serr; struct sockaddr_rxrpc srx; - struct rxrpc_local *local = sk->sk_user_data; + struct rxrpc_local *local; struct rxrpc_peer *peer; struct sk_buff *skb; - if (unlikely(!local)) + rcu_read_lock(); + local = rcu_dereference_sk_user_data(sk); + if (unlikely(!local)) { + rcu_read_unlock(); return; - + } _enter("%p{%d}", sk, local->debug_id); /* Clear the outstanding error value on the socket so that it doesn't @@ -163,6 +166,7 @@ void rxrpc_error_report(struct sock *sk) skb = sock_dequeue_err_skb(sk); if (!skb) { + rcu_read_unlock(); _leave("UDP socket errqueue empty"); return; } @@ -170,11 +174,11 @@ void rxrpc_error_report(struct sock *sk) serr = SKB_EXT_ERR(skb); if (!skb->len && serr->ee.ee_origin == SO_EE_ORIGIN_TIMESTAMPING) { _leave("UDP empty message"); + rcu_read_unlock(); rxrpc_free_skb(skb, rxrpc_skb_freed); return; } - rcu_read_lock(); peer = rxrpc_lookup_peer_icmp_rcu(local, skb, &srx); if (peer && !rxrpc_get_peer_maybe(peer)) peer = NULL; -- 2.20.1