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[209.132.180.67]) by mx.google.com with ESMTP id g69-v6si15179895plb.297.2018.08.01.03.45.16; Wed, 01 Aug 2018 03:45:30 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387665AbeHAM3h (ORCPT + 99 others); Wed, 1 Aug 2018 08:29:37 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:50352 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387462AbeHAM3h (ORCPT ); Wed, 1 Aug 2018 08:29:37 -0400 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9DAA781663F3; Wed, 1 Aug 2018 10:44:27 +0000 (UTC) Received: from localhost.localdomain (unknown [10.32.181.232]) by smtp.corp.redhat.com (Postfix) with ESMTP id 62BC4215670D; Wed, 1 Aug 2018 10:44:22 +0000 (UTC) Message-ID: <225373e97b42e0e5ee6210b329f0bbb94055b651.camel@redhat.com> Subject: Re: AW: AW: PROBLEM: Kernel Oops in UDP stack From: Paolo Abeni To: Marcel Hellwig , 'Eric Dumazet' , "'davem@davemloft.net'" , "'kuznet@ms2.inr.ac.ru'" , "'yoshfuji@linux-ipv6.org'" , "'andrew@lunn.ch'" Cc: "'netdev@vger.kernel.org'" , "'linux-kernel@vger.kernel.org'" , Matthias Wystrik Date: Wed, 01 Aug 2018 12:44:22 +0200 In-Reply-To: <9f9d731107594b368504cbbaf698bc3d@ZCOM03.mut-group.com> References: <18092446dfa7435aaa8deaab65afbf23@ZCOM03.mut-group.com> <96753ca4-88fe-aa26-b439-6e22eaf8b524@gmail.com> <9f9d731107594b368504cbbaf698bc3d@ZCOM03.mut-group.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 01 Aug 2018 10:44:27 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.8]); Wed, 01 Aug 2018 10:44:27 +0000 (UTC) for IP:'10.11.54.6' DOMAIN:'int-mx06.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'pabeni@redhat.com' RCPT:'' Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2018-08-01 at 10:35 +0000, Marcel Hellwig wrote: > > > [] (udp_recvmsg+0x284/0x33c) from [] (inet_recvmsg+0x38/0x4c): net/ipv4/udp.c:1234 > > > > sin->sin_addr.s_addr = ip_hdr(skb)->saddr; > > > > Unaligned access trap (virtual address c14fe63a), so either sin or ip_hdr(skb) are not on a 32bit alignment > > > > Can you produce the disassembly of the trapping instruction ? > > https://gist.github.com/hellow554/6b11c6c0827d5db80a7e66f71f5636ff#file-net_uipv4_udp-lst-L1892-L1895 > > sin->sin_addr.s_addr = ip_hdr(skb)->saddr; > c0228ad8: e5943080 ldr r3, [r4, #128] ; 0x80 > c0228adc: e593300c ldr r3, [r3, #12] > c0228ae0: e5823004 str r3, [r2, #4] I *think* pskb_trim_rcsum() in __udp4_lib_rcv() can copy the ipv4 header to an unaligned address, for cloned skbs. If I understood correctly the relevant socket is a mcast one, so cloned skbs can land there. Paolo