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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9C0D8CCA47F for ; Tue, 19 Jul 2022 12:49:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S241749AbiGSMtA (ORCPT ); Tue, 19 Jul 2022 08:49:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37922 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241743AbiGSMsf (ORCPT ); Tue, 19 Jul 2022 08:48:35 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B93598CCB8; Tue, 19 Jul 2022 05:19:08 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 0A9FAB81B13; Tue, 19 Jul 2022 12:18:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 727B7C341C6; Tue, 19 Jul 2022 12:18:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1658233122; bh=Xm0MwoDW/hV6tsQcoq3CJwBjGnfYANhsNhn7svWmwSM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dXRK/WK9Rw/RhkKqWul6PK1Qx7dNxGWFpuJDIKNvO3wBELI8s97vHjKP1W+tOkRo6 T47r0BJArKY3E8A1VQoZiTROjz5gbj4xlEqG3VsOP2PCnKThA9TwSZtj0Oe9EqY5Y2 GLfewqrPtjJ9DMWwFk1N5X//PAaZkdsQ4zeKqw4Q= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Juergen Gross , Jan Beulich , Paul Durrant , Jakub Kicinski Subject: [PATCH 5.18 014/231] xen/netback: avoid entering xenvif_rx_next_skb() with an empty rx queue Date: Tue, 19 Jul 2022 13:51:39 +0200 Message-Id: <20220719114715.261650516@linuxfoundation.org> X-Mailer: git-send-email 2.37.1 In-Reply-To: <20220719114714.247441733@linuxfoundation.org> References: <20220719114714.247441733@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Juergen Gross commit 94e8100678889ab428e68acadf042de723f094b9 upstream. xenvif_rx_next_skb() is expecting the rx queue not being empty, but in case the loop in xenvif_rx_action() is doing multiple iterations, the availability of another skb in the rx queue is not being checked. This can lead to crashes: [40072.537261] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [40072.537407] IP: xenvif_rx_skb+0x23/0x590 [xen_netback] [40072.537534] PGD 0 P4D 0 [40072.537644] Oops: 0000 [#1] SMP NOPTI [40072.537749] CPU: 0 PID: 12505 Comm: v1-c40247-q2-gu Not tainted 4.12.14-122.121-default #1 SLE12-SP5 [40072.537867] Hardware name: HP ProLiant DL580 Gen9/ProLiant DL580 Gen9, BIOS U17 11/23/2021 [40072.537999] task: ffff880433b38100 task.stack: ffffc90043d40000 [40072.538112] RIP: e030:xenvif_rx_skb+0x23/0x590 [xen_netback] [40072.538217] RSP: e02b:ffffc90043d43de0 EFLAGS: 00010246 [40072.538319] RAX: 0000000000000000 RBX: ffffc90043cd7cd0 RCX: 00000000000000f7 [40072.538430] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffffc90043d43df8 [40072.538531] RBP: 000000000000003f R08: 000077ff80000000 R09: 0000000000000008 [40072.538644] R10: 0000000000007ff0 R11: 00000000000008f6 R12: ffffc90043ce2708 [40072.538745] R13: 0000000000000000 R14: ffffc90043d43ed0 R15: ffff88043ea748c0 [40072.538861] FS: 0000000000000000(0000) GS:ffff880484600000(0000) knlGS:0000000000000000 [40072.538988] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [40072.539088] CR2: 0000000000000080 CR3: 0000000407ac8000 CR4: 0000000000040660 [40072.539211] Call Trace: [40072.539319] xenvif_rx_action+0x71/0x90 [xen_netback] [40072.539429] xenvif_kthread_guest_rx+0x14a/0x29c [xen_netback] Fix that by stopping the loop in case the rx queue becomes empty. Cc: stable@vger.kernel.org Fixes: 98f6d57ced73 ("xen-netback: process guest rx packets in batches") Signed-off-by: Juergen Gross Reviewed-by: Jan Beulich Reviewed-by: Paul Durrant Link: https://lore.kernel.org/r/20220713135322.19616-1-jgross@suse.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/xen-netback/rx.c | 1 + 1 file changed, 1 insertion(+) --- a/drivers/net/xen-netback/rx.c +++ b/drivers/net/xen-netback/rx.c @@ -495,6 +495,7 @@ void xenvif_rx_action(struct xenvif_queu queue->rx_copy.completed = &completed_skbs; while (xenvif_rx_ring_slots_available(queue) && + !skb_queue_empty(&queue->rx_queue) && work_done < RX_BATCH_SIZE) { xenvif_rx_skb(queue); work_done++;