ext4: fix use-after-free in ext4_rename_dir_prepare
commit
0be698ecbe4471fcad80e81ec6a05001421041b3 upstream.
We got issue as follows:
EXT4-fs (loop0): mounted filesystem without journal. Opts: ,errors=continue
ext4_get_first_dir_block: bh->b_data=0xffff88810bee6000 len=34478
ext4_get_first_dir_block: *parent_de=0xffff88810beee6ae bh->b_data=0xffff88810bee6000
ext4_rename_dir_prepare: [1] parent_de=0xffff88810beee6ae
==================================================================
BUG: KASAN: use-after-free in ext4_rename_dir_prepare+0x152/0x220
Read of size 4 at addr
ffff88810beee6ae by task rep/1895
CPU: 13 PID: 1895 Comm: rep Not tainted 5.10.0+ #241
Call Trace:
dump_stack+0xbe/0xf9
print_address_description.constprop.0+0x1e/0x220
kasan_report.cold+0x37/0x7f
ext4_rename_dir_prepare+0x152/0x220
ext4_rename+0xf44/0x1ad0
ext4_rename2+0x11c/0x170
vfs_rename+0xa84/0x1440
do_renameat2+0x683/0x8f0
__x64_sys_renameat+0x53/0x60
do_syscall_64+0x33/0x40
entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f45a6fc41c9
RSP: 002b:
00007ffc5a470218 EFLAGS:
00000246 ORIG_RAX:
0000000000000108
RAX:
ffffffffffffffda RBX:
0000000000000000 RCX:
00007f45a6fc41c9
RDX:
0000000000000005 RSI:
0000000020000180 RDI:
0000000000000005
RBP:
00007ffc5a470240 R08:
00007ffc5a470160 R09:
0000000020000080
R10:
00000000200001c0 R11:
0000000000000246 R12:
0000000000400bb0
R13:
00007ffc5a470320 R14:
0000000000000000 R15:
0000000000000000
The buggy address belongs to the page:
page:
00000000440015ce refcount:0 mapcount:0 mapping:
0000000000000000 index:0x1 pfn:0x10beee
flags: 0x200000000000000()
raw:
0200000000000000 ffffea00043ff4c8 ffffea0004325608 0000000000000000
raw:
0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff88810beee580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88810beee600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>
ffff88810beee680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff88810beee700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff88810beee780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Disabling lock debugging due to kernel taint
ext4_rename_dir_prepare: [2] parent_de->inode=
3537895424
ext4_rename_dir_prepare: [3] dir=0xffff888124170140
ext4_rename_dir_prepare: [4] ino=2
ext4_rename_dir_prepare: ent->dir->i_ino=2 parent=-
757071872
Reason is first directory entry which 'rec_len' is 34478, then will get illegal
parent entry. Now, we do not check directory entry after read directory block
in 'ext4_get_first_dir_block'.
To solve this issue, check directory entry in 'ext4_get_first_dir_block'.
[ Trigger an ext4_error() instead of just warning if the directory is
missing a '.' or '..' entry. Also make sure we return an error code
if the file system is corrupted. -TYT ]
Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220414025223.4113128-1-yebin10@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>