Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754737AbdGCNhD (ORCPT ); Mon, 3 Jul 2017 09:37:03 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:34394 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754948AbdGCNg7 (ORCPT ); Mon, 3 Jul 2017 09:36:59 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jia-Ju Bai , "David S. Miller" Subject: [PATCH 3.18 08/36] net: caif: Fix a sleep-in-atomic bug in cfpkt_create_pfx Date: Mon, 3 Jul 2017 15:34:05 +0200 Message-Id: <20170703133256.647200179@linuxfoundation.org> X-Mailer: git-send-email 2.13.2 In-Reply-To: <20170703133256.260692013@linuxfoundation.org> References: <20170703133256.260692013@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1470 Lines: 50 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Jia-Ju Bai [ Upstream commit f146e872eb12ebbe92d8e583b2637e0741440db3 ] The kernel may sleep under a rcu read lock in cfpkt_create_pfx, and the function call path is: cfcnfg_linkup_rsp (acquire the lock by rcu_read_lock) cfctrl_linkdown_req cfpkt_create cfpkt_create_pfx alloc_skb(GFP_KERNEL) --> may sleep cfserl_receive (acquire the lock by rcu_read_lock) cfpkt_split cfpkt_create_pfx alloc_skb(GFP_KERNEL) --> may sleep There is "in_interrupt" in cfpkt_create_pfx to decide use "GFP_KERNEL" or "GFP_ATOMIC". In this situation, "GFP_KERNEL" is used because the function is called under a rcu read lock, instead in interrupt. To fix it, only "GFP_ATOMIC" is used in cfpkt_create_pfx. Signed-off-by: Jia-Ju Bai Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/caif/cfpkt_skbuff.c | 6 +----- 1 file changed, 1 insertion(+), 5 deletions(-) --- a/net/caif/cfpkt_skbuff.c +++ b/net/caif/cfpkt_skbuff.c @@ -81,11 +81,7 @@ static struct cfpkt *cfpkt_create_pfx(u1 { struct sk_buff *skb; - if (likely(in_interrupt())) - skb = alloc_skb(len + pfx, GFP_ATOMIC); - else - skb = alloc_skb(len + pfx, GFP_KERNEL); - + skb = alloc_skb(len + pfx, GFP_ATOMIC); if (unlikely(skb == NULL)) return NULL;