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 ^ > !(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. > ret = -ESTALE; > goto bad_inode; > } Otherwise the patch looks good to me. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
