CVE-2026-89750

Status: UPDATED  |  Advisory ID: CVE-2026-89750

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

tracing/user_events: Clear copied tracing state before fork duplication

dup_task_struct() copies user_event_mm from the parent into the child,

without grabbing a reference to it. user_event_mm_dup() should

replace it, but it leaves that copied pointer unmodified if

user_event_mm_alloc() fails.

When the child exits, user_event_mm_remove() decrements a reference

the child never owned, which ultimately frees user_event_mm, while

the parent still as a stale pointer to it. This creates a UAF, which

KASAN reports as:

BUG: KASAN: slab-use-after-free in

current_user_event_mm+0x51/0x1d0 Write of size 4 at addr

ffff888005010d30 by task init/44

Call Trace:

<TASK>

kasan_report+0xce/0x100

kasan_check_range+0x10f/0x1e0

current_user_event_mm+0x51/0x1d0

user_events_ioctl+0x82e/0x15c0

__x64_sys_ioctl+0x139/0x1c0

do_syscall_64+0xce/0x450

entry_SYSCALL_64_after_hwframe+0x77/0x7f

Allocated by task 44:

__kasan_kmalloc+0x8f/0xa0

__kmalloc_cache_noprof+0x180/0x3a0

user_event_mm_alloc+0x3c/0x1f0

current_user_event_mm+0x88/0x1d0

Freed by task 42:

__kasan_slab_free+0x43/0x70

kfree+0x13a/0x390

process_one_work+0x696/0xf90

worker_thread+0x420/0xba0

The fix simply clears the copied pointer before any possible failure.

In case of failure, the child then has nothing to free. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References