From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752161AbcGNIoB (ORCPT ); Thu, 14 Jul 2016 04:44:01 -0400 Received: from mx2.suse.de ([195.135.220.15]:55118 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751072AbcGNIQj (ORCPT ); Thu, 14 Jul 2016 04:16:39 -0400 X-Amavis-Alert: BAD HEADER SECTION, Duplicate header field: "References" From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Herbert Xu , "David S . Miller" , Jiri Slaby Subject: [PATCH 3.12 13/88] netlink: Fix dump skb leak/double free Date: Thu, 14 Jul 2016 10:15:05 +0200 Message-Id: <461dbb3855305ad7e841799ef573d6fc2abf6ed3.1468483951.git.jslaby@suse.cz> X-Mailer: git-send-email 2.9.1 In-Reply-To: <3d4036cb9b963cdd270c02856a888183da0623db.1468483951.git.jslaby@suse.cz> References: <3d4036cb9b963cdd270c02856a888183da0623db.1468483951.git.jslaby@suse.cz> In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Herbert Xu 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ Upstream commit 92964c79b357efd980812c4de5c1fd2ec8bb5520 ] When we free cb->skb after a dump, we do it after releasing the lock. This means that a new dump could have started in the time being and we'll end up freeing their skb instead of ours. This patch saves the skb and module before we unlock so we free the right memory. Fixes: 16b304f3404f ("netlink: Eliminate kmalloc in netlink dump operation.") Reported-by: Baozeng Ding Signed-off-by: Herbert Xu Acked-by: Cong Wang Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby --- net/netlink/af_netlink.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 10805856dfba..bb04abe72d76 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2658,6 +2658,7 @@ static int netlink_dump(struct sock *sk) struct netlink_callback *cb; struct sk_buff *skb = NULL; struct nlmsghdr *nlh; + struct module *module; int len, err = -ENOBUFS; int alloc_size; @@ -2707,9 +2708,11 @@ static int netlink_dump(struct sock *sk) cb->done(cb); nlk->cb_running = false; + module = cb->module; + skb = cb->skb; mutex_unlock(nlk->cb_mutex); - module_put(cb->module); - consume_skb(cb->skb); + module_put(module); + consume_skb(skb); return 0; errout_skb: -- 2.9.1