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SubjectRe: [PATCH v2 1/2] ext4: fail ext4_iget if special inode unallocated
On Sat 07-01-23 11:21:25, 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@suse.de>
> Suggested-by: Theodore Ts'o <tytso@mit.edu>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza

> ---
> V1->V2:
> -EFSCORRUPTED is returned instead of -ESTALE for special inode
> errors, and the extra parentheses are removed.
>
> fs/ext4/inode.c | 18 ++++++++----------
> 1 file changed, 8 insertions(+), 10 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 9d9f414f99fe..ed7598127e7c 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;
> @@ -4951,11 +4944,16 @@ 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 ||
> !(EXT4_SB(inode->i_sb)->s_mount_state & EXT4_ORPHAN_FS)) &&
> ino != EXT4_BOOT_LOADER_INO) {
> - /* this inode is deleted */
> - ret = -ESTALE;
> + /* this inode is deleted or unallocated */
> + if (flags & EXT4_IGET_SPECIAL) {
> + ext4_error_inode(inode, function, line, 0,
> + "iget: special inode unallocated");
> + ret = -EFSCORRUPTED;
> + } else
> + ret = -ESTALE;
> goto bad_inode;
> }
> /* The only unlinked inodes we let through here have
> --
> 2.31.1
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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