From: OGAWA Hirofumi Date: Fri, 10 Mar 2017 00:17:37 +0000 (-0800) Subject: fat: fix using uninitialized fields of fat_inode/fsinfo_inode X-Git-Tag: firefly_0821_release~176^2^2^2~38 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=8353f338def1df3b58150cf1d6f42d1a51902b55;p=firefly-linux-kernel-4.4.55.git fat: fix using uninitialized fields of fat_inode/fsinfo_inode commit c0d0e351285161a515396b7b1ee53ec9ffd97e3c upstream. 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. Link: http://lkml.kernel.org/r/87pohrj4i8.fsf@mail.parknet.co.jp Signed-off-by: OGAWA Hirofumi Reported-by: Moreno Bartalucci Tested-by: Moreno Bartalucci Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 509411dd3698..cf644d52c0cf 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1269,6 +1269,16 @@ 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); @@ -1713,12 +1723,13 @@ int fat_fill_super(struct super_block *sb, void *data, int silent, int isvfat, 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);