quota: fix warning in dqgrab()
In the Linux kernel, the following vulnerability has been resolved:
quota: fix warning in dqgrab()
There's issue as follows when do fault injection:
WARNING: CPU: 1 PID: 14870 at include/linux/quotaops.h:51 dquot_disable+0x13b7/0x18c0
Modules linked in:
CPU: 1 PID: 14870 Comm: fsconfig Not tainted 6.3.0-next-20230505-00006-g5107a9c821af-dirty #541
RIP: 0010:dquot_disable+0x13b7/0x18c0
RSP: 0018:ffffc9000acc79e0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88825e41b980
RDX: 0000000000000000 RSI: ffff88825e41b980 RDI: 0000000000000002
RBP: ffff888179f68000 R08: ffffffff82087ca7 R09: 0000000000000000
R10: 0000000000000001 R11: ffffed102f3ed026 R12: ffff888179f68130
R13: ffff888179f68110 R14: dffffc0000000000 R15: ffff888179f68118
FS: 00007f450a073740(0000) GS:ffff88882fc00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffe96f2efd8 CR3: 000000025c8ad000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
dquot_load_quota_sb+0xd53/0x1060
dquot_resume+0x172/0x230
ext4_reconfigure+0x1dc6/0x27b0
reconfigure_super+0x515/0xa90
__x64_sys_fsconfig+0xb19/0xd20
do_syscall_64+0x39/0xb0
entry_SYSCALL_64_after_hwframe+0x63/0xcd
Above issue may happens as follows:
ProcessA ProcessB ProcessC
sys_fsconfig
vfs_fsconfig_locked
reconfigure_super
ext4_remount
dquot_suspend -> suspend all type quota
sys_fsconfig
vfs_fsconfig_locked
reconfigure_super
ext4_remount
dquot_resume
ret = dquot_load_quota_sb
add_dquot_ref
do_open -> open file O_RDWR
vfs_open
do_dentry_open
get_write_access
atomic_inc_unless_negative(&inode->i_writecount)
ext4_file_open
dquot_file_open
dquot_initialize
__dquot_initialize
dqget
atomic_inc(&dquot->dq_count);
__dquot_initialize
__dquot_initialize
dqget
if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
ext4_acquire_dquot
-> Return error DQ_ACTIVE_B flag isn't set
dquot_disable
invalidate_dquots
if (atomic_read(&dquot->dq_count))
dqgrab
WARN_ON_ONCE(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
-> Trigger warning
In the above scenario, 'dquot->dq_flags' has no DQ_ACTIVE_B is normal when
dqgrab().
To solve above issue just replace the dqgrab() use in invalidate_dquots() with
atomic_inc(&dquot->dq_count).
