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

Baokun Li
2022-10-26T04:01:36Z

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>
---
fs/quota/dquot.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 0427b44bfee5..f27faf5db554 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -2324,6 +2324,8 @@ static int vfs_setup_quota_inode(struct inode *inode, int type)
struct super_block *sb = inode->i_sb;
struct quota_info *dqopt = sb_dqopt(sb);

+ if (is_bad_inode(inode))
+ return -EUCLEAN;
if (!S_ISREG(inode->i_mode))
return -EACCES;
if (IS_RDONLY(inode))
--
2.31.1