On 2023/1/6 22:28, Jan Kara wrote:
On Fri 06-01-23 18:47:05, Baokun Li wrote:
In ext4_fill_super(), EXT4_ORPHAN_FS flag is cleared after
ext4_orphan_cleanup() is executed. Therefore, when __ext4_iget() is
called to get an inode whose i_nlink is 0 when the flag exists, no error
is returned. If the inode is a special inode, a null pointer dereference
may occur. If the value of i_nlink is 0 for any inodes (except boot loader
inodes) got by using the EXT4_IGET_SPECIAL flag, the current file system
is corrupted. Therefore, make the ext4_iget() function return an error if
it gets such an abnormal special inode.
Link: https://bugzilla.kernel.org/show_bug.cgi?id=199179
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216541
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216539
Reported-by: Luís Henriques <lhenriques@xxxxxxx>
Suggested-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Thanks for the patch! A few comments below.
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index 9d9f414f99fe..3f7cfa91ba89 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -4872,13 +4872,6 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
goto bad_inode;
raw_inode = ext4_raw_inode(&iloc);
- if ((ino == EXT4_ROOT_INO) && (raw_inode->i_links_count == 0)) {
- ext4_error_inode(inode, function, line, 0,
- "iget: root inode unallocated");
- ret = -EFSCORRUPTED;
- goto bad_inode;
- }
-
if ((flags & EXT4_IGET_HANDLE) &&
(raw_inode->i_links_count == 0) && (raw_inode->i_mode == 0)) {
ret = -ESTALE;
@@ -4951,10 +4944,13 @@ struct inode *__ext4_iget(struct super_block *sb, unsigned long ino,
* NeilBrown 1999oct15
*/
if (inode->i_nlink == 0) {
- if ((inode->i_mode == 0 ||
+ if ((inode->i_mode == 0 || (flags & EXT4_IGET_SPECIAL) ||
^ extra parenthesis here ^
Indeed, I'll remove the extra parenthesis.
!(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
ino != EXT4_BOOT_LOADER_INO) {
/* this inode is deleted */
+ if (flags & EXT4_IGET_SPECIAL)
+ ext4_error_inode(inode, function, line, 0,
+ "iget: special inode unallocated");
I think it would be better to return -EFSCORRUPTED and not -ESTALE in this
case.
Totally agree! For special inode, -EFSCORRUPTED is more reasonable.
ret = -ESTALE;
goto bad_inode;
}
Otherwise the patch looks good to me.
Honza
Thank you very much for your review！
I will send a patch V2 with the changes suggested by you.
--
With Best Regards,
Baokun Li
.
