Re: [PATCH v3 1/4] ext4: fix bug_on in __es_tree_search caused by bad quota inode

Chaitanya Kulkarni
2022-10-26T18:34:11Z

On 10/25/2022 9:23 PM, 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 the inode is
> bad_inode in vfs_setup_quota_inode().
>
> Signed-off-by: Baokun Li <libaokun1@huawei.com>

The analysis and the provided call chain looks really good, only thing
non-blocker is missing that maintainer might want it version history.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck