CVE-2026-64413: netfilter: ebtables: zero chainstack array

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

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

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

netfilter: ebtables: zero chainstack array

sashiko reports:
 looking at ebtables table
 translation, could a sparse cpu_possible_mask lead to an uninitialized pointer
 free?

 If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible,
 but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at
 CPU 2, the cleanup loop will blindly decrement and call vfree() on
 newinfo->chainstack[1].

Not a real-world bug, such allocation isn't expected to fail
in the first place.

The Linux kernel CVE team has assigned CVE-2026-64413 to this issue.


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

	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.10.261 with commit 2ade612967e2cdfb9290ebcb773f302c82f311fa
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 5.15.212 with commit 42bef500d07b5769d916e9122a3e3fa3fd2245ef
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.1.178 with commit fc7f105451044501a50cfd530cfa3b472c54acbc
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.6.145 with commit 9e6c5169db423e51dcc66a73fd15409c0d38e088
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.12.97 with commit 29bf41a9b59aff9f6197df58641a00037d567ca8
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 6.18.39 with commit 9f74d28e903fa4fdf82f870d0aeadddc8196e41c
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.1.4 with commit 5ee856e4208acafaaaf7b84824d39b78c21345d6
	Issue introduced in 2.6.12 with commit 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and fixed in 7.2-rc3 with commit cbfe53599eebffd188938ab6774cc41794f6f9d5

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-2026-64413
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:
	net/bridge/netfilter/ebtables.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/2ade612967e2cdfb9290ebcb773f302c82f311fa
	https://git.kernel.org/stable/c/42bef500d07b5769d916e9122a3e3fa3fd2245ef
	https://git.kernel.org/stable/c/fc7f105451044501a50cfd530cfa3b472c54acbc
	https://git.kernel.org/stable/c/9e6c5169db423e51dcc66a73fd15409c0d38e088
	https://git.kernel.org/stable/c/29bf41a9b59aff9f6197df58641a00037d567ca8
	https://git.kernel.org/stable/c/9f74d28e903fa4fdf82f870d0aeadddc8196e41c
	https://git.kernel.org/stable/c/5ee856e4208acafaaaf7b84824d39b78c21345d6
	https://git.kernel.org/stable/c/cbfe53599eebffd188938ab6774cc41794f6f9d5