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[209.132.180.67]) by mx.google.com with ESMTP id j62si16415528pgd.170.2019.07.24.22.59.14; Wed, 24 Jul 2019 22:59:29 -0700 (PDT) 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="zhaAk0G/"; 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 S2390782AbfGYFlt (ORCPT + 99 others); Thu, 25 Jul 2019 01:41:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:56640 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387941AbfGYFlr (ORCPT ); Thu, 25 Jul 2019 01:41:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.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 4445522C7D; Thu, 25 Jul 2019 05:41:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564033306; bh=he61A2f42ighlk64zvro43y+G1T98ICDsXNodbMcuN8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zhaAk0G/pZGyQCyjV2eQw13BFdTD+cPw4V2bpfj5/UmhW0fDGJMQGdbIoN0gC4nL5 R9wnkO+7gGNEA51PlsjNw1k/bE23jEg4PlmKceTyDAJ5fh7JQY1WHazvb9HL99ooOz 2CQevCb2rIkNAeDOOCQ2t+//UMY3nv7s9kqaqiy0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Denis Efremov , Willy Tarreau , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 161/271] floppy: fix out-of-bounds read in next_valid_format Date: Wed, 24 Jul 2019 21:20:30 +0200 Message-Id: <20190724191708.969220476@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190724191655.268628197@linuxfoundation.org> References: <20190724191655.268628197@linuxfoundation.org> User-Agent: quilt/0.66 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 [ Upstream commit 5635f897ed83fd539df78e98ba69ee91592f9bb8 ] This fixes a global out-of-bounds read access in the next_valid_format function of the floppy driver. The values from autodetect field of the struct floppy_drive_params are used as indices for the floppy_type array in the next_valid_format function 'floppy_type[DP->autodetect[probed_format]].sect'. To trigger the bug, one could use a value out of range and set the drive parameters with the FDSETDRVPRM ioctl. A floppy disk is not required to be inserted. CAP_SYS_ADMIN is required to call FDSETDRVPRM. The patch adds the check for values of the autodetect field to be in the '0 <= x < ARRAY_SIZE(floppy_type)' range of the floppy_type array indices. The bug was found by syzkaller. Signed-off-by: Denis Efremov Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- drivers/block/floppy.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index b1425b218606..dd49737effbf 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3391,6 +3391,20 @@ static int fd_getgeo(struct block_device *bdev, struct hd_geometry *geo) return 0; } +static bool valid_floppy_drive_params(const short autodetect[8]) +{ + size_t floppy_type_size = ARRAY_SIZE(floppy_type); + size_t i = 0; + + for (i = 0; i < 8; ++i) { + if (autodetect[i] < 0 || + autodetect[i] >= floppy_type_size) + return false; + } + + return true; +} + static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long param) { @@ -3517,6 +3531,8 @@ static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned int SUPBOUND(size, strlen((const char *)outparam) + 1); break; case FDSETDRVPRM: + if (!valid_floppy_drive_params(inparam.dp.autodetect)) + return -EINVAL; *UDP = inparam.dp; break; case FDGETDRVPRM: @@ -3714,6 +3730,8 @@ static int compat_setdrvprm(int drive, return -EPERM; if (copy_from_user(&v, arg, sizeof(struct compat_floppy_drive_params))) return -EFAULT; + if (!valid_floppy_drive_params(v.autodetect)) + return -EINVAL; mutex_lock(&floppy_mutex); UDP->cmos = v.cmos; UDP->max_dtr = v.max_dtr; -- 2.20.1