In the Linux kernel, the following vulnerability has been resolved:
btrfs: free exchange changeset on failures
Fstests runs on my VMs have show several kmemleak reports like the following.
unreferenced object 0xffff88811ae59080 (size 64):
comm "xfs_io", pid 12124, jiffies 4294987392 (age 6.368s)
hex dump (first 32 bytes):
00 c0 1c 00 00 00 00 00 ff cf 1c 00 00 00 00 00 ................
90 97 e5 1a 81 88 ff ff 90 97 e5 1a 81 88 ff ff ................
backtrace:
[<00000000ac0176d2>] ulist_add_merge+0x60/0x150 [btrfs]
[<0000000076e9f312>] set_state_bits+0x86/0xc0 [btrfs]
[<0000000014fe73d6>] set_extent_bit+0x270/0x690 [btrfs]
[<000000004f675208>] set_record_extent_bits+0x19/0x20 [btrfs]
[<00000000b96137b1>] qgroup_reserve_data+0x274/0x310 [btrfs]
[<0000000057e9dcbb>] btrfs_check_data_free_space+0x5c/0xa0 [btrfs]
[<0000000019c4511d>] btrfs_delalloc_reserve_space+0x1b/0xa0 [btrfs]
[<000000006d37e007>] btrfs_dio_iomap_begin+0x415/0x970 [btrfs]
[<00000000fb8a74b8>] iomap_iter+0x161/0x1e0
[<0000000071dff6ff>] __iomap_dio_rw+0x1df/0x700
[<000000002567ba53>] iomap_dio_rw+0x5/0x20
[<0000000072e555f8>] btrfs_file_write_iter+0x290/0x530 [btrfs]
[<000000005eb3d845>] new_sync_write+0x106/0x180
[<000000003fb505bf>] vfs_write+0x24d/0x2f0
[<000000009bb57d37>] __x64_sys_pwrite64+0x69/0xa0
[<000000003eba3fdf>] do_syscall_64+0x43/0x90
In case brtfs_qgroup_reserve_data() or btrfs_delalloc_reserve_metadata()
fail the allocated extent_changeset will not be freed.
So in btrfs_check_data_free_space() and btrfs_delalloc_reserve_space()
free the allocated extent_changeset to get rid of the allocated memory.
The issue currently only happens in the direct IO write path, but only
after 65b3c08606e5 ("btrfs: fix ENOSPC failure when attempting direct IO
write into NOCOW range"), and also at defrag_one_locked_target(). Every
other place is always calling extent_changeset_free() even if its call
to btrfs_delalloc_reserve_space() or btrfs_check_data_free_space() has
failed.
References
Configurations
Configuration 1 (hide)
|
History
24 Sep 2025, 19:20
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
| CWE | CWE-401 | |
| CPE | cpe:2.3:o:linux:linux_kernel:5.16:rc4:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc2:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:5.16:rc3:*:*:*:*:*:* |
|
| First Time |
Linux
Linux linux Kernel |
|
| References | () https://git.kernel.org/stable/c/ca06c5cb1b6dbfe67655b33c02fc394d65824519 - Patch | |
| References | () https://git.kernel.org/stable/c/da5e817d9d75422eaaa05490d0b9a5e328fc1a51 - Patch |
Information
Published : 2024-05-24 15:15
Updated : 2025-09-24 19:20
NVD link : CVE-2021-47508
Mitre link : CVE-2021-47508
CVE.ORG link : CVE-2021-47508
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-401
Missing Release of Memory after Effective Lifetime