Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932549AbbKLXTj (ORCPT ); Thu, 12 Nov 2015 18:19:39 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:45375 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932508AbbKLXTc (ORCPT ); Thu, 12 Nov 2015 18:19:32 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Eric Dumazet , "David S. Miller" , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 093/155] net: add pfmemalloc check in sk_add_backlog() Date: Thu, 12 Nov 2015 15:17:27 -0800 Message-Id: <1447370309-357-94-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1447370309-357-1-git-send-email-kamal@canonical.com> References: <1447370309-357-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1962 Lines: 58 3.19.8-ckt10 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit c7c49b8fde26b74277188bdc6c9dca38db6fa35b ] Greg reported crashes hitting the following check in __sk_backlog_rcv() BUG_ON(!sock_flag(sk, SOCK_MEMALLOC)); The pfmemalloc bit is currently checked in sk_filter(). This works correctly for TCP, because sk_filter() is ran in tcp_v[46]_rcv() before hitting the prequeue or backlog checks. For UDP or other protocols, this does not work, because the sk_filter() is ran from sock_queue_rcv_skb(), which might be called _after_ backlog queuing if socket is owned by user by the time packet is processed by softirq handler. Fixes: b4b9e35585089 ("netvm: set PF_MEMALLOC as appropriate during SKB processing") Signed-off-by: Eric Dumazet Reported-by: Greg Thelen Signed-off-by: David S. Miller Signed-off-by: Kamal Mostafa --- include/net/sock.h | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/include/net/sock.h b/include/net/sock.h index 45b54d3..173743e 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -825,6 +825,14 @@ static inline __must_check int sk_add_backlog(struct sock *sk, struct sk_buff *s if (sk_rcvqueues_full(sk, limit)) return -ENOBUFS; + /* + * If the skb was allocated from pfmemalloc reserves, only + * allow SOCK_MEMALLOC sockets to use it as this socket is + * helping free memory + */ + if (skb_pfmemalloc(skb) && !sock_flag(sk, SOCK_MEMALLOC)) + return -ENOMEM; + __sk_add_backlog(sk, skb); sk->sk_backlog.len += skb->truesize; return 0; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/