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[2620:137:e000::1:20]) by mx.google.com with ESMTP id b4-20020a6567c4000000b0047776c01d71si3099800pgs.375.2022.12.16.07.28.21; Fri, 16 Dec 2022 07:28:29 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=c6znUTtw; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231370AbiLPPPW (ORCPT + 68 others); Fri, 16 Dec 2022 10:15:22 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43948 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230043AbiLPPPU (ORCPT ); Fri, 16 Dec 2022 10:15:20 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FA3A26A9C; Fri, 16 Dec 2022 07:15:19 -0800 (PST) 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 dfw.source.kernel.org (Postfix) with ESMTPS id E4A566212A; Fri, 16 Dec 2022 15:15:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC0D8C433EF; Fri, 16 Dec 2022 15:15:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671203718; bh=hVmaV8eHCGnDwSv6a5ZKwe06WOILzDouZM8P5zM5OFs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=c6znUTtwqFg4NpDKlwVfpK5BPgC7FYTjMC4aXzX+13Xd5MgiAee20AVVNVaTBYE5z KJbW1dIHq2g1GfeWDnOJU6jpYx8ztqR4jJDj+0G5LNIOAprDbROaXA0JXQt5oSwU1h tfE8RjUNrsBcaWKd3n/TXnVyJI//0GKrYTBBIxs1okGN1lDkE4fRnlPI61zTTK/W2c k//WqpF/oYW+4raxiELhcgWQESiiin35CbWHmBO+H36jGIKbZzYN9rR6nLvpmQqW5P lTd7LVVCECDtP80/oYJoPAvunr3l3QwhBB9edmYyJRTDDoz3HLBTA33UdD8412KgQo oPRD6OnHheYCg== Date: Fri, 16 Dec 2022 08:15:15 -0700 From: Keith Busch To: huteng19901016@gmail.com Cc: axboe@kernel.dk, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, "huteng.ht" Subject: Re: [PATCH] blk-mq: fix possible NULL pointer access in classic polling Message-ID: References: <20221216150636.18111-1-huteng.ht@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221216150636.18111-1-huteng.ht@bytedance.com> X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Dec 16, 2022 at 11:06:36PM +0800, huteng19901016@gmail.com wrote: > From: "huteng.ht" > > Since poll method in blk_mq_ops may not be implemented by driver, > add a judgement to avoid NULL pointer access. Have you actually observed this NULL pointer access occur? Because the poll attempt should have been abandoned much earlier due to the queue not having QUEUE_FLAG_POLL set. If a driver has that flag set without actually implementing ->poll(), though, that'd be a different bug.