Subject: CVE-2024-42075: bpf: Fix remap of arena.

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

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

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

bpf: Fix remap of arena.

The bpf arena logic didn't account for mremap operation. Add a refcnt for
multiple mmap events to prevent use-after-free in arena_vm_close.

The Linux kernel CVE team has assigned CVE-2024-42075 to this issue.

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

	Issue introduced in 6.9 with commit 317460317a02 and fixed in 6.9.8 with commit 87496a1b01e8
	Issue introduced in 6.9 with commit 317460317a02 and fixed in 6.10 with commit b90d77e5fd78

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-2024-42075
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/bpf/arena.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/87496a1b01e8e2e399428c0db25e106f7961d01e
	https://git.kernel.org/stable/c/b90d77e5fd784ada62ddd714d15ee2400c28e1cf