CVE-2026-64522: net/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA

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

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

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

net/mlx5e: Fix eswitch mode block underflow on IPsec acquire SA

mlx5e_xfrm_add_state() handles acquire-flow temporary SAs by allocating
software state and skipping hardware offload setup.

That path jumps to the common success label before taking the eswitch mode
block. After tunnel-mode validation was moved earlier, the common success
label unconditionally calls mlx5_eswitch_unblock_mode(). For acquire SAs,
this decrements esw->offloads.num_block_mode without a matching increment.

Return directly after installing the acquire SA offload handle, so only the
paths that successfully called mlx5_eswitch_block_mode() call the matching
unblock.

The Linux kernel CVE team has assigned CVE-2026-64522 to this issue.


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

	Issue introduced in 6.18 with commit 22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 and fixed in 6.18.34 with commit b5bd4249e430f5963d559708ee96a671716d2400
	Issue introduced in 6.18 with commit 22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 and fixed in 7.0.11 with commit ecafd8284e527666e83261e6e57a7c7341d591cb
	Issue introduced in 6.18 with commit 22239eb258bc1e6ccdb2d3502fce1cc2b2a88386 and fixed in 7.1 with commit abe003b33223ff33552f291644bf35d9c2f992fb
	Issue introduced in 6.17.4 with commit 993c4ba71596c30418ba5a0ddcf4f9c2f431466a

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-2026-64522
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/net/ethernet/mellanox/mlx5/core/en_accel/ipsec.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/b5bd4249e430f5963d559708ee96a671716d2400
	https://git.kernel.org/stable/c/ecafd8284e527666e83261e6e57a7c7341d591cb
	https://git.kernel.org/stable/c/abe003b33223ff33552f291644bf35d9c2f992fb