CVE-2026-80675: libbpf: Reject non-exclusive metadata maps in the signed loader

CVE-2026-80675: libbpf: Reject non-exclusive metadata maps in the signed loader

[Greg Kroah-Hartman]

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

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

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

libbpf: Reject non-exclusive metadata maps in the signed loader

The loader verifies map->sha against the metadata hash in its
instructions. map->sha is calculated when BPF_OBJ_GET_INFO_BY_FD is
called on the frozen map.

While the map is frozen, the /signed loader/ must also ensure the map
is exclusive, as, without exclusivity (which a hostile host could just
omit when loading the loader), another BPF program with map access can
mutate the contents afterwards, so the check passes on stale data.

With the extra check as part of the signed loader, it now refuses to
move on with map->sha validation if the host set it up wrongly.

The Linux kernel CVE team has assigned CVE-2026-80675 to this issue.


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

	Issue introduced in 6.18 with commit fb2b0e290147ba01a53dfd92cf91058c9d2ee254 and fixed in 6.18.40 with commit b6862b6a25c6a925fb0b0e549ee4a52a8d2966fb
	Issue introduced in 6.18 with commit fb2b0e290147ba01a53dfd92cf91058c9d2ee254 and fixed in 7.1.5 with commit 0dad5adeb34b6f78a883e8faa6a1c947a240e7c9
	Issue introduced in 6.18 with commit fb2b0e290147ba01a53dfd92cf91058c9d2ee254 and fixed in 7.2 with commit 0fb6c9ed6493b4af01be8bb0a384574eba7df636

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-2026-80675
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:
	include/linux/bpf.h
	kernel/bpf/syscall.c
	tools/lib/bpf/gen_loader.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/b6862b6a25c6a925fb0b0e549ee4a52a8d2966fb
	https://git.kernel.org/stable/c/0dad5adeb34b6f78a883e8faa6a1c947a240e7c9
	https://git.kernel.org/stable/c/0fb6c9ed6493b4af01be8bb0a384574eba7df636