Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753198AbdFSSf6 (ORCPT + 2 others); Mon, 19 Jun 2017 14:35:58 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:52211 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753177AbdFSSfy (ORCPT ); Mon, 19 Jun 2017 14:35:54 -0400 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, linux@roeck-us.net Cc: Arnaldo Carvalho de Melo , Cong Wang , Eric Dumazet , Gerrit Renker , Thomas Gleixner , "David S . Miller" , Willy Tarreau Subject: [PATCH 3.10 180/268] dccp: Unlock sock before calling sk_free() Date: Mon, 19 Jun 2017 20:31:19 +0200 Message-Id: <1497897167-14556-181-git-send-email-w@1wt.eu> X-Mailer: git-send-email 2.8.0.rc2.1.gbe9624a In-Reply-To: <1497897167-14556-1-git-send-email-w@1wt.eu> References: <1497897167-14556-1-git-send-email-w@1wt.eu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: Arnaldo Carvalho de Melo commit d5afb6f9b6bb2c57bd0c05e76e12489dc0d037d9 upstream. The code where sk_clone() came from created a new socket and locked it, but then, on the error path didn't unlock it. This problem stayed there for a long while, till b0691c8ee7c2 ("net: Unlock sock before calling sk_free()") fixed it, but unfortunately the callers of sk_clone() (now sk_clone_locked()) were not audited and the one in dccp_create_openreq_child() remained. Now in the age of the syskaller fuzzer, this was finally uncovered, as reported by Dmitry: ---- 8< ---- I've got the following report while running syzkaller fuzzer on 86292b33d4b7 ("Merge branch 'akpm' (patches from Andrew)") [ BUG: held lock freed! ] 4.10.0+ #234 Not tainted ------------------------- syz-executor6/6898 is freeing memory ffff88006286cac0-ffff88006286d3b7, with a lock still held there! (slock-AF_INET6){+.-...}, at: [] spin_lock include/linux/spinlock.h:299 [inline] (slock-AF_INET6){+.-...}, at: [] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504 5 locks held by syz-executor6/6898: #0: (sk_lock-AF_INET6){+.+.+.}, at: [] lock_sock include/net/sock.h:1460 [inline] #0: (sk_lock-AF_INET6){+.+.+.}, at: [] inet_stream_connect+0x44/0xa0 net/ipv4/af_inet.c:681 #1: (rcu_read_lock){......}, at: [] inet6_csk_xmit+0x12a/0x5d0 net/ipv6/inet6_connection_sock.c:126 #2: (rcu_read_lock){......}, at: [] __skb_unlink include/linux/skbuff.h:1767 [inline] #2: (rcu_read_lock){......}, at: [] __skb_dequeue include/linux/skbuff.h:1783 [inline] #2: (rcu_read_lock){......}, at: [] process_backlog+0x264/0x730 net/core/dev.c:4835 #3: (rcu_read_lock){......}, at: [] ip6_input_finish+0x0/0x1700 net/ipv6/ip6_input.c:59 #4: (slock-AF_INET6){+.-...}, at: [] spin_lock include/linux/spinlock.h:299 [inline] #4: (slock-AF_INET6){+.-...}, at: [] sk_clone_lock+0x3d9/0x12c0 net/core/sock.c:1504 Fix it just like was done by b0691c8ee7c2 ("net: Unlock sock before calling sk_free()"). Reported-by: Dmitry Vyukov Cc: Cong Wang Cc: Eric Dumazet Cc: Gerrit Renker Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20170301153510.GE15145@kernel.org Signed-off-by: Arnaldo Carvalho de Melo Signed-off-by: David S. Miller Signed-off-by: Willy Tarreau --- net/dccp/minisocks.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c index 662071b..e47b15d 100644 --- a/net/dccp/minisocks.c +++ b/net/dccp/minisocks.c @@ -140,6 +140,7 @@ struct sock *dccp_create_openreq_child(struct sock *sk, /* It is still raw copy of parent, so invalidate * destructor and make plain sk_free() */ newsk->sk_destruct = NULL; + bh_unlock_sock(newsk); sk_free(newsk); return NULL; } -- 2.8.0.rc2.1.gbe9624a