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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 93487C11F72 for ; Mon, 12 Jul 2021 08:25:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 782256135A for ; Mon, 12 Jul 2021 08:25:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1359409AbhGLI0q (ORCPT ); Mon, 12 Jul 2021 04:26:46 -0400 Received: from mail.kernel.org ([198.145.29.99]:46876 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346551AbhGLHjh (ORCPT ); Mon, 12 Jul 2021 03:39:37 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id BA48D601FE; Mon, 12 Jul 2021 07:34:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626075274; bh=RMOrC1frwt1UylxJ7TKcgEozTKZQbIES9glVwdgUp2U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YdmbJKNVE/DPj/ULriFwjmy9JDwtgeErieivFtm8HHEmkQyb9FN8UFnPvH4Qal+s0 3Xuqb8kHJLvXqYTB1Ez3e4CTMMyrulQyA7NTLF9eFfaK9FFaYPrUB9pg71T8O3cQ7L FdMACBOZNF5+9NinlAC3dSADffoKPuJchbuB2o2I= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Tong Zhang , Hans Verkuil , Mauro Carvalho Chehab , Sasha Levin Subject: [PATCH 5.13 165/800] media: bt878: do not schedule tasklet when it is not setup Date: Mon, 12 Jul 2021 08:03:08 +0200 Message-Id: <20210712060936.195415144@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060912.995381202@linuxfoundation.org> References: <20210712060912.995381202@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: Tong Zhang [ Upstream commit a3a54bf4bddaecda8b5767209cfc703f0be2841d ] There is a problem with the tasklet in bt878. bt->tasklet is set by dvb-bt8xx.ko, and bt878.ko can be loaded independently. In this case if interrupt comes it may cause null-ptr-dereference. To solve this issue, we check if the tasklet is actually set before calling tasklet_schedule. [ 1.750438] bt878(0): irq FDSR FBUS risc_pc= [ 1.750728] BUG: kernel NULL pointer dereference, address: 0000000000000000 [ 1.752969] RIP: 0010:0x0 [ 1.757526] Call Trace: [ 1.757659] [ 1.757770] tasklet_action_common.isra.0+0x107/0x110 [ 1.758041] tasklet_action+0x22/0x30 [ 1.758237] __do_softirq+0xe0/0x29b [ 1.758430] irq_exit_rcu+0xa4/0xb0 [ 1.758618] common_interrupt+0x8d/0xa0 [ 1.758824] Signed-off-by: Tong Zhang Signed-off-by: Hans Verkuil Signed-off-by: Mauro Carvalho Chehab Signed-off-by: Sasha Levin --- drivers/media/pci/bt8xx/bt878.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/media/pci/bt8xx/bt878.c b/drivers/media/pci/bt8xx/bt878.c index 78dd35c9b65d..7ca309121fb5 100644 --- a/drivers/media/pci/bt8xx/bt878.c +++ b/drivers/media/pci/bt8xx/bt878.c @@ -300,7 +300,8 @@ static irqreturn_t bt878_irq(int irq, void *dev_id) } if (astat & BT878_ARISCI) { bt->finished_block = (stat & BT878_ARISCS) >> 28; - tasklet_schedule(&bt->tasklet); + if (bt->tasklet.callback) + tasklet_schedule(&bt->tasklet); break; } count++; -- 2.30.2