From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932430AbdJYTBi (ORCPT ); Wed, 25 Oct 2017 15:01:38 -0400 Received: from mail-yw0-f173.google.com ([209.85.161.173]:47565 "EHLO mail-yw0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932399AbdJYTBh (ORCPT ); Wed, 25 Oct 2017 15:01:37 -0400 X-Google-Smtp-Source: ABhQp+RYcF3oJa68ipDdeNigo4iS41RnK8cc0U0OVXYeyaQkh8hqEKWMdh/Dqh+1AqDqV0g32KZwMgwHlMYkoDG9Erg= MIME-Version: 1.0 In-Reply-To: References: <20171020111408.edj24tztxdptte5r@lakrids.cambridge.arm.com> <960D71EC-C1E9-4898-ACBE-543FC09483FF@gmail.com> From: Eric Dumazet Date: Wed, 25 Oct 2017 12:01:35 -0700 Message-ID: Subject: Re: v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone() To: Willem de Bruijn , Jason Wang Cc: Wei Wei , Dmitry Vyukov , Mark Rutland , linux-arm-kernel@lists.infradead.org, LKML , netdev , David Miller , Willem de Bruijn , syzkaller Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 25, 2017 at 11:49 AM, Willem de Bruijn wrote: > From skb->dev and netdev_priv, the tun device has flags 0x1002 == > IFF_TAP | IFF_NO_PI. This kernel precedes the recent support for > IFF_NAPI and IFF_NAPI_FRAGS. The allocation most likely happened > in tun_build_skb from current->task_frag. It would be a previous > allocation that left alloc_frag->offset unaligned. But perhaps this code > needs to perform alignment before setting skb->head. At least on > platforms where atomic on dataref must be aligned. +1 Bug added in commit 66ccbc9c87c2 ("tap: use build_skb() for small packet") From mboxrd@z Thu Jan 1 00:00:00 1970 From: edumazet@google.com (Eric Dumazet) Date: Wed, 25 Oct 2017 12:01:35 -0700 Subject: v4.14-rc3/arm64 DABT exception in atomic_inc() / __skb_clone() In-Reply-To: References: <20171020111408.edj24tztxdptte5r@lakrids.cambridge.arm.com> <960D71EC-C1E9-4898-ACBE-543FC09483FF@gmail.com> Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, Oct 25, 2017 at 11:49 AM, Willem de Bruijn wrote: > From skb->dev and netdev_priv, the tun device has flags 0x1002 == > IFF_TAP | IFF_NO_PI. This kernel precedes the recent support for > IFF_NAPI and IFF_NAPI_FRAGS. The allocation most likely happened > in tun_build_skb from current->task_frag. It would be a previous > allocation that left alloc_frag->offset unaligned. But perhaps this code > needs to perform alignment before setting skb->head. At least on > platforms where atomic on dataref must be aligned. +1 Bug added in commit 66ccbc9c87c2 ("tap: use build_skb() for small packet")