diff options
| author | Zhang Yi <yi.zhang@huawei.com> | 2022-06-01 17:27:17 +0800 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2022-06-18 19:36:08 -0400 |
| commit | b55c3cd102a6f48b90e61c44f7f3dda8c290c694 (patch) | |
| tree | f52b14a46633d8b38fb775dda349df54096b9a60 /fs/ext4 | |
| parent | bc75a6eb856cb1507fa907bf6c1eda91b3fef52f (diff) | |
ext4: add reserved GDT blocks check
We capture a NULL pointer issue when resizing a corrupt ext4 image which
is freshly clear resize_inode feature (not run e2fsck). It could be
simply reproduced by following steps. The problem is because of the
resize_inode feature was cleared, and it will convert the filesystem to
meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was
not reduced to zero, so could we mistakenly call reserve_backup_gdb()
and passing an uninitialized resize_inode to it when adding new group
descriptors.
mkfs.ext4 /dev/sda 3G
tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck
mount /dev/sda /mnt
resize2fs /dev/sda 8G
========
BUG: kernel NULL pointer dereference, address: 0000000000000028
CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748
...
RIP: 0010:ext4_flex_group_add+0xe08/0x2570
...
Call Trace:
<TASK>
ext4_resize_fs+0xbec/0x1660
__ext4_ioctl+0x1749/0x24e0
ext4_ioctl+0x12/0x20
__x64_sys_ioctl+0xa6/0x110
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f2dd739617b
========
The fix is simple, add a check in ext4_resize_begin() to make sure that
the es->s_reserved_gdt_blocks is zero when the resize_inode feature is
disabled.
Cc: stable@kernel.org
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Reviewed-by: Ritesh Harjani <ritesh.list@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20220601092717.763694-1-yi.zhang@huawei.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/resize.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 90a941d20dff..8b70a4701293 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -54,6 +54,16 @@ int ext4_resize_begin(struct super_block *sb) return -EPERM; /* + * If the reserved GDT blocks is non-zero, the resize_inode feature + * should always be set. + */ + if (EXT4_SB(sb)->s_es->s_reserved_gdt_blocks && + !ext4_has_feature_resize_inode(sb)) { + ext4_error(sb, "resize_inode disabled but reserved GDT blocks non-zero"); + return -EFSCORRUPTED; + } + + /* * If we are not using the primary superblock/GDT copy don't resize, * because the user tools have no way of handling this. Probably a * bad time to do it anyways. |