CVE-2026-45880: PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails

CVE-2026-45880: PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

PCI/P2PDMA: Release per-CPU pgmap ref when vm_insert_page() fails

When vm_insert_page() fails in p2pmem_alloc_mmap(), p2pmem_alloc_mmap()
doesn't invoke percpu_ref_put() to free the per-CPU ref of pgmap acquired
after gen_pool_alloc_owner(), and memunmap_pages() will hang forever when
trying to remove the PCI device.

Fix it by adding the missed percpu_ref_put().

The Linux kernel CVE team has assigned CVE-2026-45880 to this issue.


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

	Issue introduced in 6.2 with commit 7e9c7ef83d785236f5a8c3761dd053fae9b92fb8 and fixed in 6.6.128 with commit baa42b756d183a59572f3890981a3d32b8d05d40
	Issue introduced in 6.2 with commit 7e9c7ef83d785236f5a8c3761dd053fae9b92fb8 and fixed in 6.12.75 with commit 51b7181cfbedf289ce794b6d97a1c596c309ec38
	Issue introduced in 6.2 with commit 7e9c7ef83d785236f5a8c3761dd053fae9b92fb8 and fixed in 6.18.14 with commit e19cce88ec4c4877f4ff2469099b9cf23cc3e93e
	Issue introduced in 6.2 with commit 7e9c7ef83d785236f5a8c3761dd053fae9b92fb8 and fixed in 6.19.4 with commit a1f4dc72efc3204db95d052058d785cad7ce755f
	Issue introduced in 6.2 with commit 7e9c7ef83d785236f5a8c3761dd053fae9b92fb8 and fixed in 7.0 with commit 6220694c52a5a04102b48109e4f24e958b559bd3

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-2026-45880
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:
	drivers/pci/p2pdma.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/baa42b756d183a59572f3890981a3d32b8d05d40
	https://git.kernel.org/stable/c/51b7181cfbedf289ce794b6d97a1c596c309ec38
	https://git.kernel.org/stable/c/e19cce88ec4c4877f4ff2469099b9cf23cc3e93e
	https://git.kernel.org/stable/c/a1f4dc72efc3204db95d052058d785cad7ce755f
	https://git.kernel.org/stable/c/6220694c52a5a04102b48109e4f24e958b559bd3