Re: [PATCH] ext4: fix WARNING in lock_two_nondirectories

Theodore Ts'o
2023-12-25T02:49:39Z

On Mon, Dec 25, 2023 at 10:33:20AM +0800, Baokun Li wrote:
> Since in the current logic we update the boot loader file via
> swap_inode_boot_loader(), however the boot loader inode on disk
> may be uninitialized and may be garbage data, so we allow to get a
> bad boot loader inode and then initialize it and swap it with the boot
> loader file to be set.
> When reinitializing the bad boot loader inode, something like an
> inode type conversion may occur.

Yes, but the boot laoder inode is *either* all zeros, or a regular
file. If it's a directory, then it's a malicious syzbot trying to
mess with our minds.

Aside from the warning, it's pretty harmless, but it will very likely
result in a corrupted file system --- but the file system was
corrupted in the first place. So who cares?

Just check to make sure that i_mode is either 0, or regular file, and
return EFSCORRUPTEd, and we're done.

- Ted