High · published December 24, 2025
In the Linux kernel, the following vulnerability has been resolved:
ext4: turn quotas off if mount failed after enabling quotas
Yi found during a review of the patch "ext4: don't BUG on inconsistent
journal feature" that when ext4_mark_recovery_complete() returns an error
value, the error handling path does not turn off the enabled quotas,
which triggers the following kmemleak:
================================================================
unreferenced object 0xffff8cf68678e7c0 (size 64):
comm "mount", pid 746, jiffies 4294871231 (age 11.540s)
hex dump (first 32 bytes):
00 90 ef 82 f6 8c ff ff 00 00 00 00 41 01 00 00 ............A...
c7 00 00 00 bd 00 00 00 0a 00 00 00 48 00 00 00 ............H...
backtrace:
[<00000000c561ef24>] __kmem_cache_alloc_node+0x4d4/0x880
[<00000000d4e621d7>] kmalloc_trace+0x39/0x140
[<00000000837eee74>] v2_read_file_info+0x18a/0x3a0
[<0000000088f6c877>] dquot_load_quota_sb+0x2ed/0x770
[<00000000340a4782>] dquot_load_quota_inode+0xc6/0x1c0
[<0000000089a18bd5>] ext4_enable_quotas+0x17e/0x3a0 [ext4]
[<000000003a0268fa>] __ext4_fill_super+0x3448/0x3910 [ext4]
[<00000000b0f2a8a8>] ext4_fill_super+0x13d/0x340 [ext4]
[<000000004a9489c4>] get_tree_bdev+0x1dc/0x370
[<000000006e723bf1>] ext4_get_tree+0x1d/0x30 [ext4]
[<00000000c7cb663d>] vfs_get_tree+0x31/0x160
[<00000000320e1bed>] do_new_mount+0x1d5/0x480
[<00000000c074654c>] path_mount+0x22e/0xbe0
[<0000000003e97a8e>] do_mount+0x95/0xc0
[<000000002f3d3736>] __x64_sys_mount+0xc4/0x160
[<0000000027d2140c>] do_syscall_64+0x3f/0x90
================================================================
To solve this problem, we add a "failed_mount10" tag, and call
ext4_quota_off_umount() in this tag to release the enabled qoutas.