CVE-2026-72467: xprtrdma: Check frwr_wp_create() during connect

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

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

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

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

xprtrdma: Check frwr_wp_create() during connect

frwr_wp_create() creates the singleton Memory Region used to encode
padding for Write chunks whose payload length is not XDR-aligned. Its
failure paths return a negative errno and leave ep->re_write_pad_mr set
to NULL.

rpcrdma_xprt_connect() currently ignores that return value. If
frwr_wp_create() fails after the rest of the connection setup succeeds,
xprt_rdma_connect_worker() treats the connection attempt as successful
and sets XPRT_CONNECTED. A later NFS/RDMA read with a non-4-byte-aligned
receive page length reaches rpcrdma_encode_write_list(), passes the NULL
write-pad MR to encode_rdma_segment(), and dereferences it.

This is locally triggerable on an NFS/RDMA client after a connect or
reconnect hits a local MR allocation, DMA-map, MR-map, or post-send
failure; a remote peer alone cannot force the local MR setup failure.

Check the return value and fail the connect as -ENOTCONN, matching the
adjacent setup failures. This keeps XPRT_CONNECTED clear and lets the
normal reconnect path retry.

The Linux kernel CVE team has assigned CVE-2026-72467 to this issue.


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

	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 6.1.178 with commit 3b252fe1778b2cdd68283146455929801bc2abd7
	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 6.6.145 with commit dd798b76a3481e392820c3ae86ed4592858c6b0f
	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 6.12.97 with commit 6b7be4f3feae322f1c2c40a3bdc99db93574a49e
	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 6.18.40 with commit 7471e66373a4444a57ef2192f8c4081202c54f45
	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 7.1.5 with commit ef3b79edf14b6bfb0d21a26ccb0463f9cf82c6a9
	Issue introduced in 5.16 with commit 21037b8c2258ec40de3b31be9ced43ceb3b784f7 and fixed in 7.2-rc1 with commit 0f13fc7c7d2e0427517e63c739277a4cd338b0c5

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-2026-72467
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/sunrpc/xprtrdma/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/3b252fe1778b2cdd68283146455929801bc2abd7
	https://git.kernel.org/stable/c/dd798b76a3481e392820c3ae86ed4592858c6b0f
	https://git.kernel.org/stable/c/6b7be4f3feae322f1c2c40a3bdc99db93574a49e
	https://git.kernel.org/stable/c/7471e66373a4444a57ef2192f8c4081202c54f45
	https://git.kernel.org/stable/c/ef3b79edf14b6bfb0d21a26ccb0463f9cf82c6a9
	https://git.kernel.org/stable/c/0f13fc7c7d2e0427517e63c739277a4cd338b0c5