Messages in this thread | | | Date | Sat, 7 Jan 2023 09:37:53 +0800 | Subject | Re: [PATCH 1/2] ext4: fail ext4_iget if special inode unallocated | From | Baokun Li <> |
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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@suse.de> >> Suggested-by: Theodore Ts'o <tytso@mit.edu> >> Signed-off-by: Baokun Li <libaokun1@huawei.com> > 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 .
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