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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 267C0C47254 for ; Tue, 5 May 2020 08:21:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C52E2068E for ; Tue, 5 May 2020 08:21:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726337AbgEEIVb (ORCPT ); Tue, 5 May 2020 04:21:31 -0400 Received: from mga18.intel.com ([134.134.136.126]:64275 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725766AbgEEIVa (ORCPT ); Tue, 5 May 2020 04:21:30 -0400 IronPort-SDR: 2cvwDrCknwWzSM4z8qGNa8cItZHzAgskZ7ZAtXExpInBTlT5yjvoqRUgku/NfNDDlcjiFO8pPP r0VH41nf6Kzw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 May 2020 01:21:29 -0700 IronPort-SDR: uALX4vBNqI6oR7zVVgMuwTZ31VgSAujfozQ1cBn9Lwlusex1nz6z5N0Xvshz+57bUnRztvAYqU +4PaxwDnXeAA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,354,1583222400"; d="scan'208";a="259616754" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by orsmga003.jf.intel.com with ESMTP; 05 May 2020 01:21:27 -0700 Subject: Re: [PATCH] usb: xhci: Fix NULL pointer dereference as part of completion To: Sriharsha Allenki , mathias.nyman@intel.com, gregkh@linuxfoundation.org Cc: linux-usb@vger.kernel.org, mgautam@codeaurora.org, jackp@codeaurora.org, stable@vger.kernel.org References: <20200505061446.21850-1-sallenki@codeaurora.org> From: Mathias Nyman Openpgp: preference=signencrypt Autocrypt: addr=mathias.nyman@linux.intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20200505061446.21850-1-sallenki@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On 5.5.2020 9.14, Sriharsha Allenki wrote: > On platforms with IOMMU enabled, multiple SGs can be > coalesced into one by the IOMMU driver. In that case > the SG list processing as part of the completion of > a urb on a bulk endpoint can result into a NULL pointer > dereference with the below stack dump. > > <6> Unable to handle kernel NULL pointer dereference at virtual address 0000000c > <6> pgd = c0004000 > <6> [0000000c] *pgd=00000000 > <6> Internal error: Oops: 5 [#1] PREEMPT SMP ARM > <2> PC is at xhci_queue_bulk_tx+0x454/0x80c > <2> LR is at xhci_queue_bulk_tx+0x44c/0x80c > <2> pc : [] lr : [] psr: 000000d3 > <2> sp : ca337c80 ip : 00000000 fp : ffffffff > <2> r10: 00000000 r9 : 50037000 r8 : 00004000 > <2> r7 : 00000000 r6 : 00004000 r5 : 00000000 r4 : 00000000 > <2> r3 : 00000000 r2 : 00000082 r1 : c2c1a200 r0 : 00000000 > <2> Flags: nzcv IRQs off FIQs off Mode SVC_32 ISA ARM Segment none > <2> Control: 10c0383d Table: b412c06a DAC: 00000051 > <6> Process usb-storage (pid: 5961, stack limit = 0xca336210) > > <2> [] (xhci_queue_bulk_tx) > <2> [] (xhci_urb_enqueue) > <2> [] (usb_hcd_submit_urb) > <2> [] (usb_sg_wait) > <2> [] (usb_stor_bulk_transfer_sglist) > <2> [] (usb_stor_bulk_srb) > <2> [] (usb_stor_Bulk_transport) > <2> [] (usb_stor_invoke_transport) > <2> [] (usb_stor_control_thread) > <2> [] (kthread) > > The above NULL pointer dereference is the result of block_len and > the sent_len set to zero after the first SG of the list when IOMMU > driver is enabled. Because of this the loop of processing the SGs > has run more than num_sgs which resulted in a sg_next on the > last SG of the list which has SG_END set. > > Fix this by check for the sg before any attributes of the sg are > accessed. > > Fixes: f9c589e142d04 ("xhci: TD-fragment, align the unsplittable case with a bounce buffer") > Cc: stable@vger.kernel.org > Signed-off-by: Sriharsha Allenki > --- > drivers/usb/host/xhci-ring.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c > index a78787bb5133..18141b38f7bf 100644 > --- a/drivers/usb/host/xhci-ring.c > +++ b/drivers/usb/host/xhci-ring.c > @@ -3399,8 +3399,8 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags, > /* New sg entry */ > --num_sgs; > sent_len -= block_len; > - if (num_sgs != 0) { > - sg = sg_next(sg); > + sg = sg_next(sg); > + if (num_sgs != 0 && sg) { > block_len = sg_dma_len(sg); > addr = (u64) sg_dma_address(sg); > addr += sent_len; > Nice catch, thanks. Adding to queue. -Mathias