Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933819AbeAJIke (ORCPT + 1 other); Wed, 10 Jan 2018 03:40:34 -0500 Received: from a.mx.secunet.com ([62.96.220.36]:45426 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933496AbeAJIkc (ORCPT ); Wed, 10 Jan 2018 03:40:32 -0500 Date: Wed, 10 Jan 2018 09:40:29 +0100 From: Steffen Klassert To: Dmitry Vyukov CC: Herbert Xu , David Miller , netdev , LKML , Eric Biggers , syzkaller Subject: Re: AF_KEY: memory leak in key_notify_policy Message-ID: <20180110084029.sz3mrfggec3hti43@gauss3.secunet.de> References: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) X-G-Data-MailSecurity-for-Exchange-State: 0 X-G-Data-MailSecurity-for-Exchange-Error: 0 X-G-Data-MailSecurity-for-Exchange-Sender: 23 X-G-Data-MailSecurity-for-Exchange-Server: d65e63f7-5c15-413f-8f63-c0d707471c93 X-EXCLAIMER-MD-CONFIG: 2c86f778-e09b-4440-8b15-867914633a10 X-G-Data-MailSecurity-for-Exchange-Guid: 7293C080-1ACB-4652-8F3A-780C26B835C6 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On Tue, Jan 09, 2018 at 06:23:54PM +0100, Dmitry Vyukov wrote: > Hello, > > syzkaller has hit the following memory leak on 4.15-rc7: > > unreferenced object 0xffff88001ea69cc0 (size 232): > comm "syz-executor6", pid 4338, jiffies 4294719848 (age 11.965s) > hex dump (first 32 bytes): > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ > backtrace: > [<000000004139cfa6>] kmemleak_alloc_recursive > include/linux/kmemleak.h:55 [inline] > [<000000004139cfa6>] slab_post_alloc_hook mm/slab.h:440 [inline] > [<000000004139cfa6>] slab_alloc_node mm/slub.c:2725 [inline] > [<000000004139cfa6>] kmem_cache_alloc_node+0x12d/0x2a0 mm/slub.c:2761 > [<0000000071fee1f9>] __alloc_skb+0x103/0x7c0 net/core/skbuff.c:193 > [<00000000b7305c65>] alloc_skb include/linux/skbuff.h:983 [inline] > [<00000000b7305c65>] pfkey_xfrm_policy2msg_prep+0x29/0x50 > net/key/af_key.c:2029 > [<000000008b2518b3>] key_notify_policy net/key/af_key.c:2192 [inline] > [<000000008b2518b3>] pfkey_send_policy_notify+0x47f/0x920 > net/key/af_key.c:3065 > [<0000000038eae3c6>] km_policy_notify+0x198/0x330 net/xfrm/xfrm_state.c:1907 > [<000000000c1a40c2>] xfrm_add_policy+0x733/0x9a0 net/xfrm/xfrm_user.c:1613 > [<000000001c692c3f>] xfrm_user_rcv_msg+0x454/0x890 net/xfrm/xfrm_user.c:2591 > [<0000000048c3aba7>] netlink_rcv_skb+0x275/0x550 > net/netlink/af_netlink.c:2408 > [<00000000649d0c12>] xfrm_netlink_rcv+0x6f/0x90 net/xfrm/xfrm_user.c:2599 > [<00000000c67992ca>] netlink_unicast_kernel > net/netlink/af_netlink.c:1275 [inline] > [<00000000c67992ca>] netlink_unicast+0x567/0x710 > net/netlink/af_netlink.c:1301 > [<00000000614f28d1>] netlink_sendmsg+0x9c4/0xf60 > net/netlink/af_netlink.c:1864 > [<000000004abc1891>] sock_sendmsg_nosec net/socket.c:636 [inline] > [<000000004abc1891>] sock_sendmsg+0xd2/0x120 net/socket.c:646 > [<0000000067a5f2bd>] ___sys_sendmsg+0x7f6/0x930 net/socket.c:2026 > [<00000000ba6aef1c>] __sys_sendmsg+0xe6/0x220 net/socket.c:2060 > [<0000000051af4885>] SYSC_sendmsg net/socket.c:2071 [inline] > [<0000000051af4885>] SyS_sendmsg+0x36/0x60 net/socket.c:2067 > [<00000000e00c5f48>] entry_SYSCALL_64_fastpath+0x23/0x9a > > It seems that key_notify_policy() fails to free the skb when > pfkey_xfrm_policy2msg() fails. Right, I plan to fix it with the following patch: Subject: [PATCH] af_key: Fix memory leak in key_notify_policy. We leak the allocated out_skb in case pfkey_xfrm_policy2msg() fails. Fix this by freeing it on error. Reported-by: Dmitry Vyukov Signed-off-by: Steffen Klassert --- net/key/af_key.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/key/af_key.c b/net/key/af_key.c index d40861a048fe..7e2e7188e7f4 100644 --- a/net/key/af_key.c +++ b/net/key/af_key.c @@ -2202,8 +2202,10 @@ static int key_notify_policy(struct xfrm_policy *xp, int dir, const struct km_ev return PTR_ERR(out_skb); err = pfkey_xfrm_policy2msg(out_skb, xp, dir); - if (err < 0) + if (err < 0) { + kfree_skb(out_skb); return err; + } out_hdr = (struct sadb_msg *) out_skb->data; out_hdr->sadb_msg_version = PF_KEY_V2; -- 2.14.1