From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> commit bc87302a093f0eab45cd4e250c2021299f712ec6 upstream. When get an error in the middle of reading an inode, some fields in the inode might be still not initialized. And then the evict_inode path may access those fields via iput(). To fix, this makes sure that inode fields are initialized. Reported-by: syzbot+9d82b8de2992579da5d0@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Link: http://lkml.kernel.org/r/871rqnreqx.fsf@xxxxxxxxxxxxxxxxxx Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/fat/inode.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -736,6 +736,13 @@ static struct inode *fat_alloc_inode(str return NULL; init_rwsem(&ei->truncate_lock); + /* Zeroing to allow iput() even if partial initialized inode. */ + ei->mmu_private = 0; + ei->i_start = 0; + ei->i_logstart = 0; + ei->i_attrs = 0; + ei->i_pos = 0; + return &ei->vfs_inode; } @@ -1366,16 +1373,6 @@ 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); @@ -1820,13 +1817,11 @@ int fat_fill_super(struct super_block *s fat_inode = new_inode(sb); if (!fat_inode) goto out_fail; - 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);
