Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751957AbdCHPXt (ORCPT ); Wed, 8 Mar 2017 10:23:49 -0500 Received: from mail.parknet.co.jp ([210.171.160.6]:60027 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750727AbdCHPXp (ORCPT ); Wed, 8 Mar 2017 10:23:45 -0500 From: OGAWA Hirofumi To: Andrew Morton Cc: moreno.bartalucci@tecnorama.it, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: [PATCH] fat: Fix using uninitialized fields of fat_inode/fsinfo_inode Date: Wed, 08 Mar 2017 22:13:19 +0900 Message-ID: <87pohrj4i8.fsf@mail.parknet.co.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1.91 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1734 Lines: 56 Recently fallocate patch was merged and it uses MSDOS_I(inode)->mmu_private at fat_evict_inode(). However, fat_inode/fsinfo_inode that was introduced in past didn't initialize MSDOS_I(inode) properly. With those combinations, it became the cause of accessing random entry in FAT area. Reported-by: Moreno Bartalucci Tested-by: Moreno Bartalucci CC: stable@vger.kernel.org Signed-off-by: OGAWA Hirofumi --- fs/fat/inode.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff -puN fs/fat/inode.c~fat-fix-fsinfo_inode fs/fat/inode.c --- linux/fs/fat/inode.c~fat-fix-fsinfo_inode 2017-03-07 12:34:54.507838051 +0900 +++ linux-hirofumi/fs/fat/inode.c 2017-03-08 03:48:37.877751531 +0900 @@ -1359,6 +1359,16 @@ out: return 0; } +static void fat_dummy_inode_init(struct inode *inode) +{ + /* Initialize this dummy inode to work as no-op. */ + MSDOS_I(inode)->mmu_private = 0; + MSDOS_I(inode)->i_start = 0; + MSDOS_I(inode)->i_logstart = 0; + MSDOS_I(inode)->i_attrs = 0; + MSDOS_I(inode)->i_pos = 0; +} + static int fat_read_root(struct inode *inode) { struct msdos_sb_info *sbi = MSDOS_SB(inode->i_sb); @@ -1803,12 +1813,13 @@ int fat_fill_super(struct super_block *s fat_inode = new_inode(sb); if (!fat_inode) goto out_fail; - MSDOS_I(fat_inode)->i_pos = 0; + fat_dummy_inode_init(fat_inode); sbi->fat_inode = fat_inode; fsinfo_inode = new_inode(sb); if (!fsinfo_inode) goto out_fail; + fat_dummy_inode_init(fsinfo_inode); fsinfo_inode->i_ino = MSDOS_FSINFO_INO; sbi->fsinfo_inode = fsinfo_inode; insert_inode_hash(fsinfo_inode); _ -- OGAWA Hirofumi