CVE-2026-64370: posix-cpu-timers: Fix pid refcount leak in do_cpu_nanosleep() error path

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

posix-cpu-timers: Fix pid refcount leak in do_cpu_nanosleep() error path

In do_cpu_nanosleep(), posix_cpu_timer_create() takes a pid reference
via get_pid() and stores it in timer.it.cpu.pid. If the subsequent
posix_cpu_timer_set() call fails, the function returns immediately
without calling posix_cpu_timer_del() to release the pid reference,
causing a leak.

Fix it by calling posix_cpu_timer_del() before the unlock-and-return
on the error path, consistent with the other exit paths in the same
function.

The Linux kernel CVE team has assigned CVE-2026-64370 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.261 with commit afed3cdc1cca133f804fcf57ff228974f424b23a
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.212 with commit 8a270b1258797f61b61da44f8bfd41a581b5c85b
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.178 with commit d605d00085adc3fddf67de01dc2a44aebf1a3fb5
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.145 with commit e5ffc638faf5dc7d9dc85c9a95e10bf97442e0c0
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.96 with commit eb4cec29a78334d09bcfb41c0660cdd62ba05843
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.39 with commit 7776f9226e99eb49d97492b0b445027cfcb189da
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.4 with commit 8f06363446c5d043c9a7c008b250040e9de98cf9
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc1 with commit 87bd2ad568e15b90d5f7d4bcd70342d05dad649c

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64370
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	kernel/time/posix-cpu-timers.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/afed3cdc1cca133f804fcf57ff228974f424b23a
	https://git.kernel.org/stable/c/8a270b1258797f61b61da44f8bfd41a581b5c85b
	https://git.kernel.org/stable/c/d605d00085adc3fddf67de01dc2a44aebf1a3fb5
	https://git.kernel.org/stable/c/e5ffc638faf5dc7d9dc85c9a95e10bf97442e0c0
	https://git.kernel.org/stable/c/eb4cec29a78334d09bcfb41c0660cdd62ba05843
	https://git.kernel.org/stable/c/7776f9226e99eb49d97492b0b445027cfcb189da
	https://git.kernel.org/stable/c/8f06363446c5d043c9a7c008b250040e9de98cf9
	https://git.kernel.org/stable/c/87bd2ad568e15b90d5f7d4bcd70342d05dad649c