CVE-2026-68419: RDMA/irdma: Prevent rereg_mr for non-mem regions

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

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

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

RDMA/irdma: Prevent rereg_mr for non-mem regions

When a QP/CQ/SRQ is created, a two step process is used
where the buffer is allocated in userspace and explicitly
registered with the normal reg_mr mechanism prior to creating
the actual QP/CQ/SRQ object.

These special registrations are indicated via an ABI field
so the driver knows that they do not have a valid mkey and
to skip the actual CQP command submission.

Since these are real MR objects from the core's perspective,
it is possible for a user application to invoke rereg_mr on them
and cause a real CQP op to be emitted with the zero-initialized
mkey value of 0.

Fix this by preventing rereg_mr on these special regions.

The Linux kernel CVE team has assigned CVE-2026-68419 to this issue.


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

	Issue introduced in 6.6.120 with commit 715fdb3b30541cc8180b7cdc6aa9f8c307afdf25 and fixed in 6.6.148 with commit fb46d134e1b8690bed2da9005b36d32d2efd34ac
	Issue introduced in 6.7 with commit 5ac388db27c443dadfbb0b8b23fa7ccf429d901a and fixed in 6.12.101 with commit b5029e91c63406e4f4c8d58161048b41b6f0bd8c
	Issue introduced in 6.7 with commit 5ac388db27c443dadfbb0b8b23fa7ccf429d901a and fixed in 6.18.42 with commit ca1c29f05274b737dc964e28b97803750d7cf7ec
	Issue introduced in 6.7 with commit 5ac388db27c443dadfbb0b8b23fa7ccf429d901a and fixed in 7.1.6 with commit dbaa37e060918c45517786e37ecab0f300b48fa9
	Issue introduced in 6.7 with commit 5ac388db27c443dadfbb0b8b23fa7ccf429d901a and fixed in 7.2-rc4 with commit a846aecb931b4d65d5eafa92a0623545af46d4f2

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-2026-68419
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/infiniband/hw/irdma/verbs.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/fb46d134e1b8690bed2da9005b36d32d2efd34ac
	https://git.kernel.org/stable/c/b5029e91c63406e4f4c8d58161048b41b6f0bd8c
	https://git.kernel.org/stable/c/ca1c29f05274b737dc964e28b97803750d7cf7ec
	https://git.kernel.org/stable/c/dbaa37e060918c45517786e37ecab0f300b48fa9
	https://git.kernel.org/stable/c/a846aecb931b4d65d5eafa92a0623545af46d4f2