From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id F2742C4346E for ; Thu, 24 Sep 2020 03:46:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D6CC23600 for ; Thu, 24 Sep 2020 03:46:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="oDBjTppI" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726662AbgIXDq3 (ORCPT ); Wed, 23 Sep 2020 23:46:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43366 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726553AbgIXDq3 (ORCPT ); Wed, 23 Sep 2020 23:46:29 -0400 Received: from mail-oo1-xc30.google.com (mail-oo1-xc30.google.com [IPv6:2607:f8b0:4864:20::c30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4E73AC0613CE for ; Wed, 23 Sep 2020 20:46:29 -0700 (PDT) Received: by mail-oo1-xc30.google.com with SMTP id m25so441696oou.0 for ; Wed, 23 Sep 2020 20:46:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:subject:message-id:mime-version :content-disposition:user-agent; bh=/D3TUiX3fVcm7eeRMzDMLamuFR1Z+NNvRtWWlZaFt4U=; b=oDBjTppI1QmFoHuFvHz0OR0YoVjJI5dSZ05Q8SuE0N7EnAs96S8wsBz/PKPdfDek4D J4DtkIefD+sRPvvg17DX0KpKWdxwSAyjQdJUXv4xO5czQsdwOK1tlym7hUApVLqOatvz dcRgybjvmPmRvsG52LkDncOCi4JeLlPMQDTRZl0PhtfRDdNqAA1hsgLYp84i3q5NElEV mlxUhTioACA8za0VurwwABf2LEJEvO+c/UXiohWGM39ZGDw6n3cgCv34yL8NwuUcKMzj TU6eTY2L5Dz9A0SWVV7LVCecmWnRdxhmfvflWfMzOjFSH568uccTFq7aXcvuEDn2REzZ ctYg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:subject:message-id :mime-version:content-disposition:user-agent; bh=/D3TUiX3fVcm7eeRMzDMLamuFR1Z+NNvRtWWlZaFt4U=; b=G21HbXwqyHKW4TOhjGr/jWN2U7bSp6qCD1I821lFIPlAB9CLyms7R7lUo30tsrw5F5 viYGzNFHw5soMyvmUo+tdW+a4L/gniphpD89K88I0CILfFQhFrZlOjQbAv2jsPUHZWrp GRg4eXddPZ3S+AXbiIKQURbE3vDVxJtqtD5B+ODv9rubY/DdDw0rjeG3MHJBXZYQ6KjP NLTVUCjgCrRERoiZt64sSjlWanb//zx0UJANJLTBRt6/57ly85NOZMLUUKV4UBcynnWi GDS3nxw1FVnBqsIcTD1k3n+hJtvfIyCY2uF6ZQspxCUvrfVRHrEErvv6+5VPKeMsl+vr I1nQ== X-Gm-Message-State: AOAM531bhX1kIj21lE0d70fEtTFJYbK5fDTbrNWI8OouMe9+wHvbfebc qMT0Hhx8lUuQvt/Hr3rVHYW3fElintY= X-Google-Smtp-Source: ABdhPJxW1jx0WcAnIh0KzpPSqGwOMmJx4ufA92+MJlKZ3f5g0zHOUluPbyISDGlon/P8Jo9TeDtftw== X-Received: by 2002:a4a:7055:: with SMTP id b21mr1961406oof.26.1600919188221; Wed, 23 Sep 2020 20:46:28 -0700 (PDT) Received: from localhost ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id m8sm529908otn.66.2020.09.23.20.46.27 for (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 23 Sep 2020 20:46:27 -0700 (PDT) Sender: Guenter Roeck Date: Wed, 23 Sep 2020 20:46:26 -0700 From: Guenter Roeck To: netdev@vger.kernel.org Subject: skb_under_panic with corrupt (?) head/data pointers Message-ID: <20200924034626.GA226842@roeck-us.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Hi, we are seeing situations where skb_under_panic is reported with bad data pointers. A recent example is [1], but we have seen more of the same. Some random examples: skb_under_panic: text:0000000039ea4f04 len:272 put:48 head:00000000bdd3f564 data:00000000f70d12b8 tail:0x102 end:0x2c0 dev:wlan0 skb_under_panic: text:0000000063ae0b92 len:822 put:48 head:000000004ae66619 data:0000000082f8ca57 tail:0x328 end:0x6c0 dev:wlan0 skb_under_panic: text:0000000056205094 len:272 put:48 head:000000003aad43d6 data:00000000e8cd088c tail:0x102 end:0x2c0 dev:wlan0 skb_under_panic: text:00000000413c3f8c len:368 put:48 head:00000000ddd1266f data:00000000f13009ae tail:0x162 end:0x2c0 dev:wlan0 skb_under_panic: text:00000000917c4645 len:520 put:48 head:000000007108f7f3 data:000000003d260246 tail:0x1fa end:0x6c0 dev:wlan0 This specific condition happens rarely; we do see lots of 'normal' skb_under_panic crashes (with valid head and data pointers) in the same driver. I would assume that the skbs are corrupted, but then I noticed a similar pattern in some kernel commit logs. commit 7901cd97963d: skb_under_panic: text:00000000ca46ad8a len:80 put:20 head:00000000cd28494e data:000000009366fd6b tail:0x3c end:0xec0 dev:veth0 commit 7901cd97963d: skb_under_panic: text:000000001d390b3a len:31 put:24 head:00000000d8ed776f data:000000008150e823 tail:0x7 end:0xc0 dev:gre0 Is there some situation where skb->head and possibly skb->data may not be initialized correctly ? Thanks, Guenter --- [1] https://www.spinics.net/lists/linux-wireless/msg200403.html