Re: [PATCH v2 1/2] ext4: fix bug_on in __es_tree_search caused by wrong s_usr_quota_inum

[Jan Kara <jack@suse.cz>]

On Fri 21-10-22 12:07:30, Baokun Li wrote:
> We got a issue as fllows:
> ==================================================================
>  kernel BUG at fs/ext4/extents_status.c:202!
>  invalid opcode: 0000 [#1] PREEMPT SMP
>  CPU: 1 PID: 810 Comm: mount Not tainted 6.1.0-rc1-next-g9631525255e3 #352
>  RIP: 0010:__es_tree_search.isra.0+0xb8/0xe0
>  RSP: 0018:ffffc90001227900 EFLAGS: 00010202
>  RAX: 0000000000000000 RBX: 0000000077512a0f RCX: 0000000000000000
>  RDX: 0000000000000002 RSI: 0000000000002a10 RDI: ffff8881004cd0c8
>  RBP: ffff888177512ac8 R08: 47ffffffffffffff R09: 0000000000000001
>  R10: 0000000000000001 R11: 00000000000679af R12: 0000000000002a10
>  R13: ffff888177512d88 R14: 0000000077512a10 R15: 0000000000000000
>  FS: 00007f4bd76dbc40(0000)GS:ffff88842fd00000(0000)knlGS:0000000000000000
>  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>  CR2: 00005653bf993cf8 CR3: 000000017bfdf000 CR4: 00000000000006e0
>  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>  Call Trace:
>   <TASK>
>   ext4_es_cache_extent+0xe2/0x210
>   ext4_cache_extents+0xd2/0x110
>   ext4_find_extent+0x5d5/0x8c0
>   ext4_ext_map_blocks+0x9c/0x1d30
>   ext4_map_blocks+0x431/0xa50
>   ext4_getblk+0x82/0x340
>   ext4_bread+0x14/0x110
>   ext4_quota_read+0xf0/0x180
>   v2_read_header+0x24/0x90
>   v2_check_quota_file+0x2f/0xa0
>   dquot_load_quota_sb+0x26c/0x760
>   dquot_load_quota_inode+0xa5/0x190
>   ext4_enable_quotas+0x14c/0x300
>   __ext4_fill_super+0x31cc/0x32c0
>   ext4_fill_super+0x115/0x2d0
>   get_tree_bdev+0x1d2/0x360
>   ext4_get_tree+0x19/0x30
>   vfs_get_tree+0x26/0xe0
>   path_mount+0x81d/0xfc0
>   do_mount+0x8d/0xc0
>   __x64_sys_mount+0xc0/0x160
>   do_syscall_64+0x35/0x80
>   entry_SYSCALL_64_after_hwframe+0x63/0xcd
>   </TASK>
> ==================================================================
> 
> Above issue may happen as follows:
> -------------------------------------
> ext4_fill_super
>  ext4_orphan_cleanup
>   ext4_enable_quotas
>    ext4_quota_enable
>     ext4_iget --> get error inode <5>
>      ext4_ext_check_inode --> Wrong imode makes it escape inspection
>      make_bad_inode(inode) --> EXT4_BOOT_LOADER_INO set imode
>     dquot_load_quota_inode
>      vfs_setup_quota_inode --> check pass
>      dquot_load_quota_sb
>       v2_check_quota_file
>        v2_read_header
>         ext4_quota_read
>          ext4_bread
>           ext4_getblk
>            ext4_map_blocks
>             ext4_ext_map_blocks
>              ext4_find_extent
>               ext4_cache_extents
>                ext4_es_cache_extent
>                 __es_tree_search.isra.0
>                  ext4_es_end --> Wrong extents trigger BUG_ON
> 
> In the above issue, s_usr_quota_inum is set to 5, but inode<5> contains
> incorrect imode and disordered extents. Because 5 is EXT4_BOOT_LOADER_INO,
> the ext4_ext_check_inode check in the ext4_iget function can be bypassed,
> finally, the extents that are not checked trigger the BUG_ON in the
> __es_tree_search function. To solve this issue, check whether qf_inode
> obtained by ext4_iget is bad_inode.
> 
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

Looks good to me. Feel free to add:

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

								Honza

> ---
>  fs/ext4/super.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ext4/super.c b/fs/ext4/super.c
> index 7a57dadfe256..5a5f95c6a0cb 100644
> --- a/fs/ext4/super.c
> +++ b/fs/ext4/super.c
> @@ -6907,9 +6907,9 @@ static int ext4_quota_enable(struct super_block *sb, int type, int format_id,
>  		return -EPERM;
>  
>  	qf_inode = ext4_iget(sb, qf_inums[type], EXT4_IGET_SPECIAL);
> -	if (IS_ERR(qf_inode)) {
> +	if (IS_ERR(qf_inode) || is_bad_inode(qf_inode)) {
>  		ext4_error(sb, "Bad quota inode # %lu", qf_inums[type]);
> -		return PTR_ERR(qf_inode);
> +		return IS_ERR(qf_inode) ? PTR_ERR(qf_inode) : -EUCLEAN;
>  	}
>  
>  	/* Don't account quota for quota files to avoid recursion */
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR