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[209.132.180.67]) by mx.google.com with ESMTP id g10si3753753plq.371.2018.12.14.04.03.44; Fri, 14 Dec 2018 04:04:20 -0800 (PST) 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; dkim=pass header.i=@kernel.org header.s=default header.b=Kceqkb4a; 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 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729925AbeLNMCC (ORCPT + 99 others); Fri, 14 Dec 2018 07:02:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:44672 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729918AbeLNMCB (ORCPT ); Fri, 14 Dec 2018 07:02:01 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.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 1DDD62146F; Fri, 14 Dec 2018 12:01:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1544788919; bh=wTY/i1Pil+En3cM6QReBPgSfN+FVgHe5nysM2HBkG0U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Kceqkb4a1R6t7nh6xEFuE4D9MtRKHmul0xDTn2nGMqHWtFA8eaXF9fSsqfFgjQfbC GH7DI4C8SuQ84AJGWAxJZl6JB6ESL7PXC2ja57OlA9HV7PW1Z1T78+cQyNm26o9+// Zdxi6hMlg1W96fbYLY+7Ocb0AAkVWowoSC0WPVIc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Prashant Bhole , Tyler Hicks , Eric Dumazet , Christoph Paasch , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.19 009/142] net: Prevent invalid access to skb->prev in __qdisc_drop_all Date: Fri, 14 Dec 2018 12:58:14 +0100 Message-Id: <20181214115747.421377117@linuxfoundation.org> X-Mailer: git-send-email 2.20.0 In-Reply-To: <20181214115747.053633987@linuxfoundation.org> References: <20181214115747.053633987@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore 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 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christoph Paasch [ Upstream commit 9410d386d0a829ace9558336263086c2fbbe8aed ] __qdisc_drop_all() accesses skb->prev to get to the tail of the segment-list. With commit 68d2f84a1368 ("net: gro: properly remove skb from list") the skb-list handling has been changed to set skb->next to NULL and set the list-poison on skb->prev. With that change, __qdisc_drop_all() will panic when it tries to dereference skb->prev. Since commit 992cba7e276d ("net: Add and use skb_list_del_init().") __list_del_entry is used, leaving skb->prev unchanged (thus, pointing to the list-head if it's the first skb of the list). This will make __qdisc_drop_all modify the next-pointer of the list-head and result in a panic later on: [ 34.501053] general protection fault: 0000 [#1] SMP KASAN PTI [ 34.501968] CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.20.0-rc2.mptcp #108 [ 34.502887] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.5.1 01/01/2011 [ 34.504074] RIP: 0010:dev_gro_receive+0x343/0x1f90 [ 34.504751] Code: e0 48 c1 e8 03 42 80 3c 30 00 0f 85 4a 1c 00 00 4d 8b 24 24 4c 39 65 d0 0f 84 0a 04 00 00 49 8d 7c 24 38 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 74 08 3c 04 [ 34.507060] RSP: 0018:ffff8883af507930 EFLAGS: 00010202 [ 34.507761] RAX: 0000000000000007 RBX: ffff8883970b2c80 RCX: 1ffff11072e165a6 [ 34.508640] RDX: 1ffff11075867008 RSI: ffff8883ac338040 RDI: 0000000000000038 [ 34.509493] RBP: ffff8883af5079d0 R08: ffff8883970b2d40 R09: 0000000000000062 [ 34.510346] R10: 0000000000000034 R11: 0000000000000000 R12: 0000000000000000 [ 34.511215] R13: 0000000000000000 R14: dffffc0000000000 R15: ffff8883ac338008 [ 34.512082] FS: 0000000000000000(0000) GS:ffff8883af500000(0000) knlGS:0000000000000000 [ 34.513036] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 34.513741] CR2: 000055ccc3e9d020 CR3: 00000003abf32000 CR4: 00000000000006e0 [ 34.514593] Call Trace: [ 34.514893] [ 34.515157] napi_gro_receive+0x93/0x150 [ 34.515632] receive_buf+0x893/0x3700 [ 34.516094] ? __netif_receive_skb+0x1f/0x1a0 [ 34.516629] ? virtnet_probe+0x1b40/0x1b40 [ 34.517153] ? __stable_node_chain+0x4d0/0x850 [ 34.517684] ? kfree+0x9a/0x180 [ 34.518067] ? __kasan_slab_free+0x171/0x190 [ 34.518582] ? detach_buf+0x1df/0x650 [ 34.519061] ? lapic_next_event+0x5a/0x90 [ 34.519539] ? virtqueue_get_buf_ctx+0x280/0x7f0 [ 34.520093] virtnet_poll+0x2df/0xd60 [ 34.520533] ? receive_buf+0x3700/0x3700 [ 34.521027] ? qdisc_watchdog_schedule_ns+0xd5/0x140 [ 34.521631] ? htb_dequeue+0x1817/0x25f0 [ 34.522107] ? sch_direct_xmit+0x142/0xf30 [ 34.522595] ? virtqueue_napi_schedule+0x26/0x30 [ 34.523155] net_rx_action+0x2f6/0xc50 [ 34.523601] ? napi_complete_done+0x2f0/0x2f0 [ 34.524126] ? kasan_check_read+0x11/0x20 [ 34.524608] ? _raw_spin_lock+0x7d/0xd0 [ 34.525070] ? _raw_spin_lock_bh+0xd0/0xd0 [ 34.525563] ? kvm_guest_apic_eoi_write+0x6b/0x80 [ 34.526130] ? apic_ack_irq+0x9e/0xe0 [ 34.526567] __do_softirq+0x188/0x4b5 [ 34.527015] irq_exit+0x151/0x180 [ 34.527417] do_IRQ+0xdb/0x150 [ 34.527783] common_interrupt+0xf/0xf [ 34.528223] This patch makes sure that skb->prev is set to NULL when entering netem_enqueue. Cc: Prashant Bhole Cc: Tyler Hicks Cc: Eric Dumazet Fixes: 68d2f84a1368 ("net: gro: properly remove skb from list") Suggested-by: Eric Dumazet Signed-off-by: Christoph Paasch Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_netem.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -441,6 +441,9 @@ static int netem_enqueue(struct sk_buff int count = 1; int rc = NET_XMIT_SUCCESS; + /* Do not fool qdisc_drop_all() */ + skb->prev = NULL; + /* Random duplication */ if (q->duplicate && q->duplicate >= get_crandom(&q->dup_cor)) ++count;