CVE-2022-50067 [High] | Use-After-Free in Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: btrfs: unset reloc control if transaction commit fails in prepare_to_relocate() In btrfs_relocate_block_group(), the rc is allocated. Then btrfs_relocate_block_group() calls relocate_block_group() prepare_to_relocate() set_reloc_control() that assigns rc to the variable fs_info->reloc_ctl. When prepare_to_relocate() returns, it calls btrfs_commit_transaction() btrfs_start_dirty_block_groups() btrfs_alloc_path() kmem_cache_zalloc() which may fail for example (or other errors could happen). When the failure occurs, btrfs_relocate_block_group() detects the error and frees rc and doesn't set fs_info->reloc_ctl to NULL. After that, in btrfs_init_reloc_root(), rc is retrieved from fs_info->reloc_ctl and then used, which may cause a use-after-free bug. This possible bug can be triggered by calling btrfs_ioctl_balance() before calling btrfs_ioctl_defrag(). To fix this possible bug, in prepare_to_relocate(), check if btrfs_commit_transaction() fails. If the failure occurs, unset_reloc_control() is called to set fs_info->reloc_ctl to NULL. The error log in our fault-injection testing is shown as follows: [ 58.751070] BUG: KASAN: use-after-free in btrfs_init_reloc_root+0x7ca/0x920 [btrfs] ... [ 58.753577] Call Trace: ... [ 58.755800] kasan_report+0x45/0x60 [ 58.756066] btrfs_init_reloc_root+0x7ca/0x920 [btrfs] [ 58.757304] record_root_in_trans+0x792/0xa10 [btrfs] [ 58.757748] btrfs_record_root_in_trans+0x463/0x4f0 [btrfs] [ 58.758231] start_transaction+0x896/0x2950 [btrfs] [ 58.758661] btrfs_defrag_root+0x250/0xc00 [btrfs] [ 58.759083] btrfs_ioctl_defrag+0x467/0xa00 [btrfs] [ 58.759513] btrfs_ioctl+0x3c95/0x114e0 [btrfs] ... [ 58.768510] Allocated by task 23683: [ 58.768777] ____kasan_kmalloc+0xb5/0xf0 [ 58.769069] __kmalloc+0x227/0x3d0 [ 58.769325] alloc_reloc_control+0x10a/0x3d0 [btrfs] [ 58.769755] btrfs_relocate_block_group+0x7aa/0x1e20 [btrfs] [ 58.770228] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.770655] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.771071] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.771472] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.771902] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ... [ 58.773337] Freed by task 23683: ... [ 58.774815] kfree+0xda/0x2b0 [ 58.775038] free_reloc_control+0x1d6/0x220 [btrfs] [ 58.775465] btrfs_relocate_block_group+0x115c/0x1e20 [btrfs] [ 58.775944] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.776369] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.776784] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.777185] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.777621] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ...

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-14	0.02%	0.05%	+0.03%
2	2025-06-18	—	0.02%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-14

0.02%

0.05%

+0.03%

2025-06-18

—

0.02%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.8	3.1	HIGH	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H` Click to expand Attack vector (AV:L) They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:L) A normal user session is enough; they don’t have to be admin. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	1.8	5.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.8

3.1

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H Click to expand

Attack vector (AV:L): They already need access on the box, or another person has to do something wrong; it’s not a remote drive-by.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L): A normal user session is enough; they don’t have to be admin.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

1.8

5.9

[email protected]

OS Trackers for CVE-2022-50067

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2022-50067 not yet assigned priority: Debian including 1 source packages (linux), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2022-50067
`redhat`	—	—	https://access.redhat.com/security/cve/CVE-2022-50067
`suse`	medium	—	https://www.suse.com/security/cve/CVE-2022-50067/
`ubuntu`	medium	CVE-2022-50067 medium priority: Ubuntu including 158 source packages (linux, linux-allwinner-5.19, …), 1551 status rows across 10 suites (bionic, focal, jammy, noble, oracular, plucky, questing, trusty, upstream, xenial): DNE 1145, released 158, ignored 148, not-affected 98, needed 1, needs-triage 1.	https://ubuntu.com/security/CVE-2022-50067

Affected software / configurations for CVE-2022-50067

Vendor	Product	Version	Raw CPE
linux	linux_kernel	< 4.14.318	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.15, < 4.19.286	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 4.20, < 5.4.247	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.5, < 5.10.184	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.11, < 5.15.63	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	>= 5.16, < 5.19.4	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.0	cpe:2.3:o:linux:linux_kernel:6.0:rc1::::::

References for CVE-2022-50067

URL	Tags
https://git.kernel.org/stable/c/5d741afed0bac206640cc64d77b97853283cf719	Patch
https://git.kernel.org/stable/c/78f8c2370e3d33e35f23bdc648653d779aeacb6e	Patch
https://git.kernel.org/stable/c/85f02d6c856b9f3a0acf5219de6e32f58b9778eb	Patch
https://git.kernel.org/stable/c/8e546674031fc1576da501e27a8fd165222e5a37	Patch
https://git.kernel.org/stable/c/b60e862e133f646f19023ece1d476d630a660de1	Patch
https://git.kernel.org/stable/c/dcb11fe0a0a9cca2b7425191b9bf30dc29f2ad0f	Patch
https://git.kernel.org/stable/c/ff0e8ed8dfb584575cffc1561f17a1d094e8565b	Patch

URL

CVE-2022-50067 | btrfs: unset reloc control if transaction commit fails in prepare_to_relocate()

Exploit prediction scoring system (EPSS) score for CVE-2022-50067

Common vulnerability scoring system (CVSS) metrics for CVE-2022-50067

Weakness enumeration for CVE-2022-50067

OS Trackers for CVE-2022-50067

Affected software / configurations for CVE-2022-50067

References for CVE-2022-50067