In the Linux kernel, the following vulnerability has been resolved:
kthread: consolidate kthread exit paths to prevent use-after-free
Guillaume reported crashes via corrupted RCU callback function pointers
during KUnit testing. The crash was traced back to the pidfs rhashtable
conversion which replaced the 24-byte rb_node with an 8-byte rhash_head
in struct pid, shrinking it from 160 to 144 bytes.
struct kthread (without CONFIG_BLK_CGROUP) is also 144 bytes. With
CONFIG_SLAB_MERGE_DEFAULT and SLAB_HWCACHE_ALIGN both round up to
192 bytes and share the same slab cache. struct pid.rcu.func and
struct kthread.affinity_node both sit at offset 0x78.
When a kthread exits via make_task_dead() it bypasses kthread_exit() and
misses the affinity_node cleanup. free_kthread_struct() frees the memory
while the node is still linked into the global kthread_affinity_list. A
subsequent list_del() by another kthread writes through dangling list
pointers into the freed and reused memory, corrupting the pid's
rcu.func pointer.
Instead of patching free_kthread_struct() to handle the missed cleanup,
consolidate all kthread exit paths. Turn kthread_exit() into a macro
that calls do_exit() and add kthread_do_exit() which is called from
do_exit() for any task with PF_KTHREAD set. This guarantees that
kthread-specific cleanup always happens regardless of the exit path -
make_task_dead(), direct do_exit(), or kthread_exit().
Replace __to_kthread() with a new tsk_is_kthread() accessor in the
public header. Export do_exit() since module code using the
kthread_exit() macro now needs it directly.
References
Configurations
Configuration 1 (hide)
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History
21 May 2026, 19:24
| Type | Values Removed | Values Added |
|---|---|---|
| CWE | CWE-416 | |
| First Time |
Linux linux Kernel
Linux |
|
| CPE | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:* |
|
| References | () https://git.kernel.org/stable/c/28aaa9c39945b7925a1cc1d513c8f21ed38f5e4f - Patch | |
| References | () https://git.kernel.org/stable/c/4729c7b00a347fd37d0cbc265b85f2884c3e06b6 - Patch | |
| References | () https://git.kernel.org/stable/c/5a591d7a5e48d30100943940a30a6ab41b15c672 - Patch |
11 May 2026, 08:16
| Type | Values Removed | Values Added |
|---|---|---|
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 9.8 |
08 May 2026, 15:16
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2026-05-08 15:16
Updated : 2026-05-21 19:24
NVD link : CVE-2026-43402
Mitre link : CVE-2026-43402
CVE.ORG link : CVE-2026-43402
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-416
Use After Free