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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 1349AC4360C for ; Sun, 6 Oct 2019 17:33:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DE3BE2133F for ; Sun, 6 Oct 2019 17:33:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570383224; bh=jbJz3uGLLHAyYLPhnl1Y9VCga/2gkSJPt8N1e4A7zik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=hVJkfS+0dRwwhMn8CuLmidZV6clJ8NI7gOITb4iBOfW0cUPNIrqKAmNJd54xJTVOW YT5aSX1anMwXIgmzbmPvmzPbTSK24gCIT0vby2TLfnfP33TZoZpzomVIUyIgP0Pj4w Ts+u4hNTWnXa6Huf1TJm5HpS8tL8mew57RRNmkMc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729803AbfJFRdl (ORCPT ); Sun, 6 Oct 2019 13:33:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:60192 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729789AbfJFRdi (ORCPT ); Sun, 6 Oct 2019 13:33:38 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 156BE2087E; Sun, 6 Oct 2019 17:33:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1570383216; bh=jbJz3uGLLHAyYLPhnl1Y9VCga/2gkSJPt8N1e4A7zik=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ydNpADY/AmNTvih4OtrvpHcpfOod6Pyo+ooLN/sjuuoS6mj52FRshUrvGSphfBM+I nPoMtjoArsoYnNQrLkwnb6PB7ObUjBAzKIcxgzPaEGHsXvbt/8TmmD/wusVJn/5UkT /7ohGaZYjAmk/Rz1+xkEElrn1m01uf1aC4+A3270= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dongli Zhang , Juergen Gross , "David S. Miller" Subject: [PATCH 5.2 022/137] xen-netfront: do not use ~0U as error return value for xennet_fill_frags() Date: Sun, 6 Oct 2019 19:20:06 +0200 Message-Id: <20191006171211.127681565@linuxfoundation.org> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191006171209.403038733@linuxfoundation.org> References: <20191006171209.403038733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Dongli Zhang [ Upstream commit a761129e3625688310aecf26e1be9e98e85f8eb5 ] xennet_fill_frags() uses ~0U as return value when the sk_buff is not able to cache extra fragments. This is incorrect because the return type of xennet_fill_frags() is RING_IDX and 0xffffffff is an expected value for ring buffer index. In the situation when the rsp_cons is approaching 0xffffffff, the return value of xennet_fill_frags() may become 0xffffffff which xennet_poll() (the caller) would regard as error. As a result, queue->rx.rsp_cons is set incorrectly because it is updated only when there is error. If there is no error, xennet_poll() would be responsible to update queue->rx.rsp_cons. Finally, queue->rx.rsp_cons would point to the rx ring buffer entries whose queue->rx_skbs[i] and queue->grant_rx_ref[i] are already cleared to NULL. This leads to NULL pointer access in the next iteration to process rx ring buffer entries. The symptom is similar to the one fixed in commit 00b368502d18 ("xen-netfront: do not assume sk_buff_head list is empty in error handling"). This patch changes the return type of xennet_fill_frags() to indicate whether it is successful or failed. The queue->rx.rsp_cons will be always updated inside this function. Fixes: ad4f15dc2c70 ("xen/netfront: don't bug in case of too many frags") Signed-off-by: Dongli Zhang Reviewed-by: Juergen Gross Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netfront.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -887,9 +887,9 @@ static int xennet_set_skb_gso(struct sk_ return 0; } -static RING_IDX xennet_fill_frags(struct netfront_queue *queue, - struct sk_buff *skb, - struct sk_buff_head *list) +static int xennet_fill_frags(struct netfront_queue *queue, + struct sk_buff *skb, + struct sk_buff_head *list) { RING_IDX cons = queue->rx.rsp_cons; struct sk_buff *nskb; @@ -908,7 +908,7 @@ static RING_IDX xennet_fill_frags(struct if (unlikely(skb_shinfo(skb)->nr_frags >= MAX_SKB_FRAGS)) { queue->rx.rsp_cons = ++cons + skb_queue_len(list); kfree_skb(nskb); - return ~0U; + return -ENOENT; } skb_add_rx_frag(skb, skb_shinfo(skb)->nr_frags, @@ -919,7 +919,9 @@ static RING_IDX xennet_fill_frags(struct kfree_skb(nskb); } - return cons; + queue->rx.rsp_cons = cons; + + return 0; } static int checksum_setup(struct net_device *dev, struct sk_buff *skb) @@ -1045,8 +1047,7 @@ err: skb->data_len = rx->status; skb->len += rx->status; - i = xennet_fill_frags(queue, skb, &tmpq); - if (unlikely(i == ~0U)) + if (unlikely(xennet_fill_frags(queue, skb, &tmpq))) goto err; if (rx->flags & XEN_NETRXF_csum_blank) @@ -1056,7 +1057,7 @@ err: __skb_queue_tail(&rxq, skb); - queue->rx.rsp_cons = ++i; + i = ++queue->rx.rsp_cons; work_done++; }