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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 29150C7618B for ; Fri, 26 Jul 2019 13:50:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E8F4722CD8 for ; Fri, 26 Jul 2019 13:50:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564149042; bh=8bKqOjSUUQC1mnRNDLkjrxM4PpNvEvT4NFD5HvX0/1g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=JLVmDqpOkmcS8yvl5d+aRW5q+LhY/vtzJq9vYBx+pv8jyPusSO73cg8nalCdpWdj+ DzsgTIjPbRl1SgBkSev4yWnaiOimB8q3CF2Z9F7D+mFsRgsF+Kb65NTpYqEPrO4iv8 CDhPJor9eVlNFNVvpZchkzJgnR2e0QS7c1dvrtWk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2387558AbfGZNuk (ORCPT ); Fri, 26 Jul 2019 09:50:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:52556 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728096AbfGZNoW (ORCPT ); Fri, 26 Jul 2019 09:44:22 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8DE5222CD8; Fri, 26 Jul 2019 13:44:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564148661; bh=8bKqOjSUUQC1mnRNDLkjrxM4PpNvEvT4NFD5HvX0/1g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nPtuQRW0/diSn3YIaUDnob/F7aGKpOXza4ldm6pYi+3h7hMCNJB6uIPzU8x8etQ33 pKMnamOPa8Z7IeRRFTCo5nJ9lhl65UkcQ9AS+lOpZr/zU03VeEtODxDkkNcl2reyGD 0IH+yX5dLEfr02zQke4U9mCSxheiucCWGC7E9Axs= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Denis Efremov , Willy Tarreau , Linus Torvalds , Sasha Levin , linux-block@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 31/37] floppy: fix out-of-bounds read in copy_buffer Date: Fri, 26 Jul 2019 09:43:26 -0400 Message-Id: <20190726134332.12626-31-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190726134332.12626-1-sashal@kernel.org> References: <20190726134332.12626-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Denis Efremov [ Upstream commit da99466ac243f15fbba65bd261bfc75ffa1532b6 ] This fixes a global out-of-bounds read access in the copy_buffer function of the floppy driver. The FDDEFPRM ioctl allows one to set the geometry of a disk. The sect and head fields (unsigned int) of the floppy_drive structure are used to compute the max_sector (int) in the make_raw_rw_request function. It is possible to overflow the max_sector. Next, max_sector is passed to the copy_buffer function and used in one of the memcpy calls. An unprivileged user could trigger the bug if the device is accessible, but requires a floppy disk to be inserted. The patch adds the check for the .sect * .head multiplication for not overflowing in the set_geometry function. 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 | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c index 4c6c20376a83..1205472a9f63 100644 --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3239,8 +3239,10 @@ static int set_geometry(unsigned int cmd, struct floppy_struct *g, int cnt; /* sanity checking for parameters. */ - if (g->sect <= 0 || - g->head <= 0 || + if ((int)g->sect <= 0 || + (int)g->head <= 0 || + /* check for overflow in max_sector */ + (int)(g->sect * g->head) <= 0 || /* check for zero in F_SECT_PER_TRACK */ (unsigned char)((g->sect << 2) >> FD_SIZECODE(g)) == 0 || g->track <= 0 || g->track > UDP->tracks >> STRETCH(g) || -- 2.20.1