CVE-2026-89535: svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id

CVE-2026-89535: svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id

[Greg Kroah-Hartman]

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

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

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

svcrdma: Reorder rpcrdma_rn_unregister before rdma_destroy_id

svc_rdma_free() caches rdma->sc_cm_id->device before teardown,
then calls rdma_destroy_id(sc_cm_id) which frees the cm_id.
rpcrdma_rn_unregister() follows, but between those two calls
the transport's sc_rn entry is still installed in the device's
rd_xa. A concurrent ib_unregister_device walk can dispatch
svc_rdma_xprt_done() against the now-freed sc_cm_id.

Move rpcrdma_rn_unregister() before rdma_destroy_id() so the
transport's notification entry is removed from the xarray before
the cm_id it references is destroyed.

Also guard the sc_cm_id dereference with a NULL check: the
following patches introduce paths that reach svc_rdma_free()
with sc_cm_id == NULL (listener create failure, ADDR_CHANGE
replacement failure).

The Linux kernel CVE team has assigned CVE-2026-89535 to this issue.


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

	Issue introduced in 6.12 with commit c4de97f7c45434985e5dbf2d6ccc9eca676e37fe and fixed in 6.18.51 with commit 9f2f5d0999364c7070306cd422d8babc2621070d
	Issue introduced in 6.12 with commit c4de97f7c45434985e5dbf2d6ccc9eca676e37fe and fixed in 7.2.4 with commit cfca6eb3345ba4a23cf9a1153ad09bf19faabfc9
	Issue introduced in 6.12 with commit c4de97f7c45434985e5dbf2d6ccc9eca676e37fe and fixed in 7.3-rc1 with commit 4488e912973773d64368828acf3b8e39d93650ae

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-2026-89535
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/svc_rdma_transport.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/9f2f5d0999364c7070306cd422d8babc2621070d
	https://git.kernel.org/stable/c/cfca6eb3345ba4a23cf9a1153ad09bf19faabfc9
	https://git.kernel.org/stable/c/4488e912973773d64368828acf3b8e39d93650ae