CVE-2026-74305: bpf: Tighten cgroup storage cookie checks for prog arrays

CVE-2026-74305: bpf: Tighten cgroup storage cookie checks for prog arrays

[Greg Kroah-Hartman]

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

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

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

bpf: Tighten cgroup storage cookie checks for prog arrays

The fix in commit abad3d0bad72 ("bpf: Fix oob access in cgroup local
storage") is still incomplete. The prog-array compatibility check
treats a program with no cgroup storage as compatible with any stored
storage cookie. This allows a storage-less program to bridge a tail
call chain between an entry program and a storage-using callee even
though cgroup local storage at runtime still follows the caller's
context, that is, A -> B(no storage) -> C(storage) path.

Requiring exact cookie equality would break the legitimate case of a
storage-less leaf program being tail called from a storage-using one.
Instead, only accept a zero storage cookie if the program cannot
perform tail calls itself. This keeps A -> B(no storage) working
while rejecting the A -> B(no storage) -> C(storage) bridge.

The Linux kernel CVE team has assigned CVE-2026-74305 to this issue.


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

	Issue introduced in 5.15.192 with commit c1c74584b9b4043c52e41fec415226e582d266a3 and fixed in 5.15.212 with commit 87177497cca90bf4fcfb759eb898560eb5b46a10
	Issue introduced in 6.1.151 with commit 66da7cee78590259b400e51a70622ccd41da7bb2 and fixed in 6.1.178 with commit 1c762d28698483ce7c372091f34d86e4d4828652
	Issue introduced in 6.6.105 with commit 7acfa07c585e3d7a64654d38f0a5c762877d0b9b and fixed in 6.6.145 with commit eb73056ce2a6f101ddd3bdba89af6b24ebffff85
	Issue introduced in 6.12.46 with commit 41688d1fc5d163a6c2c0e95c0419e2cb31a44648 and fixed in 6.12.97 with commit 9ca06849c4239aa2d580c54651f8588c51cb398b
	Issue introduced in 6.17 with commit abad3d0bad72a52137e0c350c59542d75ae4f513 and fixed in 6.18.40 with commit 46fbafe3d2d569d828e8d24a7dbe1659f63685cf
	Issue introduced in 6.17 with commit abad3d0bad72a52137e0c350c59542d75ae4f513 and fixed in 7.1.5 with commit cb22dc79528eb26a46d346c3118dbd6b14c70609
	Issue introduced in 6.17 with commit abad3d0bad72a52137e0c350c59542d75ae4f513 and fixed in 7.2-rc1 with commit 10627ddc0167aab5c1c390a10ef461e9937aba08
	Issue introduced in 6.16.1 with commit 19341d5c59e8c7e8528e40f8663e99d67810473c

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-2026-74305
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/core.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/87177497cca90bf4fcfb759eb898560eb5b46a10
	https://git.kernel.org/stable/c/1c762d28698483ce7c372091f34d86e4d4828652
	https://git.kernel.org/stable/c/eb73056ce2a6f101ddd3bdba89af6b24ebffff85
	https://git.kernel.org/stable/c/9ca06849c4239aa2d580c54651f8588c51cb398b
	https://git.kernel.org/stable/c/46fbafe3d2d569d828e8d24a7dbe1659f63685cf
	https://git.kernel.org/stable/c/cb22dc79528eb26a46d346c3118dbd6b14c70609
	https://git.kernel.org/stable/c/10627ddc0167aab5c1c390a10ef461e9937aba08