From patchwork Wed Jul 5 15:09:42 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Geert Uytterhoeven X-Patchwork-Id: 9826659 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id AE02460361 for ; Wed, 5 Jul 2017 15:09:49 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id A4B8626E3E for ; Wed, 5 Jul 2017 15:09:49 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9913228555; Wed, 5 Jul 2017 15:09:49 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3177926E3E for ; Wed, 5 Jul 2017 15:09:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751891AbdGEPJr (ORCPT ); Wed, 5 Jul 2017 11:09:47 -0400 Received: from albert.telenet-ops.be ([195.130.137.90]:59802 "EHLO albert.telenet-ops.be" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751680AbdGEPJq (ORCPT ); Wed, 5 Jul 2017 11:09:46 -0400 Received: from ayla.of.borg ([84.195.106.246]) by albert.telenet-ops.be with bizsmtp id h39k1v0035JzmfG0639kiV; Wed, 05 Jul 2017 17:09:44 +0200 Received: from ramsan.of.borg ([192.168.97.29] helo=ramsan) by ayla.of.borg with esmtp (Exim 4.86_2) (envelope-from ) id 1dSlw0-0007Wc-Cg; Wed, 05 Jul 2017 17:09:44 +0200 Received: from geert by ramsan with local (Exim 4.86_2) (envelope-from ) id 1dSlw0-0007PS-Bm; Wed, 05 Jul 2017 17:09:44 +0200 From: Geert Uytterhoeven To: Ulf Hansson , Linus Walleij Cc: Arnd Bergmann , linux-mmc@vger.kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven Subject: [PATCH v2 2/2] mmc: block: Let MMC_IOC_MULTI_CMD return zero again for zero entries Date: Wed, 5 Jul 2017 17:09:42 +0200 Message-Id: <1499267382-28438-2-git-send-email-geert@linux-m68k.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1499267382-28438-1-git-send-email-geert@linux-m68k.org> References: <1499267382-28438-1-git-send-email-geert@linux-m68k.org> MIME-Version: 1.0 Sender: linux-mmc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-mmc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP With gcc 4.1.2: drivers/mmc/core/block.c: In function ‘mmc_blk_ioctl_cmd_issue’: drivers/mmc/core/block.c:630: warning: ‘ioc_err’ may be used uninitialized in this function Indeed, if mq_rq->ioc_count is zero, an uninitialized value will be stored in mq_rq->drv_op_result and passed to blk_end_request_all(). Can mq_rq->ioc_count be zero? - mmc_blk_ioctl_cmd() sets ioc_count to 1, so this is safe, - mmc_blk_ioctl_multi_cmd() obtains ioc_count from user space in response to the MMC_IOC_MULTI_CMD ioctl, and does allow zero. To avoid returning an uninitialized value, and as it is pointless to do all this work when the MMC_IOC_MULTI_CMD ioctl is used with zero entries, check for this early in mmc_blk_ioctl_multi_cmd(), and return zero, like was returned before. Fixes: 3ecd8cf23f88d5df ("mmc: block: move multi-ioctl() to use block layer") Signed-off-by: Geert Uytterhoeven --- Should mmc_blk_ioctl_multi_cmd() return -EINVAL instead for this case? That would change behavior as seen from userspace, though. Feel free to fold in the previous patch if deemed appropriate. v2: - No changes. --- drivers/mmc/core/block.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c index 4920ea1ece38a9b6..e0363223996e6096 100644 --- a/drivers/mmc/core/block.c +++ b/drivers/mmc/core/block.c @@ -637,6 +637,9 @@ static int mmc_blk_ioctl_multi_cmd(struct block_device *bdev, sizeof(num_of_cmds))) return -EFAULT; + if (!num_of_cmds) + return 0; + if (num_of_cmds > MMC_IOC_MAX_CMDS) return -EINVAL;