CVE-2026-68139: net/mlx5e: Use sender devcom for MPV master-up

CVE-2026-68139: net/mlx5e: Use sender devcom for MPV master-up

[Greg Kroah-Hartman]

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

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

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

net/mlx5e: Use sender devcom for MPV master-up

After PCIe DPC recovery, mlx5 reloads the affected functions and
replays multiport affiliation events. In the reported failure, the
first relevant device error was:

  pcieport 0000:10:01.1: DPC: containment event
  pcieport 0000:10:01.1: PCIe Bus Error: severity=Uncorrected (Fatal)
  pcieport 0000:10:01.1:    [ 5] SDES                   (First)

mlx5 recovered the PCI functions and resumed 0000:11:00.1. During
that resume, RDMA multiport binding replayed
MLX5_DRIVER_EVENT_AFFILIATION_DONE and mlx5e sent
MPV_DEVCOM_MASTER_UP. The host then panicked with:

  BUG: kernel NULL pointer dereference, address: 0000000000000010
  RIP: mlx5_devcom_comp_set_ready+0x5/0x40 [mlx5_core]
  RDI: 0000000000000000

Call trace included:

  mlx5_devcom_comp_set_ready
  mlx5e_devcom_event_mpv
  mlx5_devcom_send_event
  mlx5_ib_bind_slave_port
  mlx5r_mp_probe
  mlx5_pci_resume

MPV devcom registration publishes mlx5e private data to the component
peer list before mlx5e_devcom_init_mpv() stores the returned component
device in priv->devcom. A concurrent master-up event can therefore
reach a peer whose private data is visible but whose priv->devcom
backpointer is still NULL.

MPV_DEVCOM_MASTER_UP already carries the sender/master mlx5e private
data as event_data. The ready bit is stored on the shared devcom
component, not on an individual peer. Use the sender devcom when
marking the MPV component ready.

This preserves the readiness transition while avoiding a NULL
dereference of the peer devcom pointer during affiliation replay after
PCI error recovery.

The Linux kernel CVE team has assigned CVE-2026-68139 to this issue.


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

	Issue introduced in 6.7 with commit bf11485f8419f90ffaa3804fd01d8468fcc56e23 and fixed in 6.12.101 with commit c698b2735613f1f35c55688bd2252f75f31c49ad
	Issue introduced in 6.7 with commit bf11485f8419f90ffaa3804fd01d8468fcc56e23 and fixed in 6.18.42 with commit 40f9a124ebbe0d60fe165fb3f87515c35b2d72f5
	Issue introduced in 6.7 with commit bf11485f8419f90ffaa3804fd01d8468fcc56e23 and fixed in 7.1.6 with commit a60c81f168c9fe4f5d84302d1e32b717f5a8a933
	Issue introduced in 6.7 with commit bf11485f8419f90ffaa3804fd01d8468fcc56e23 and fixed in 7.2-rc5 with commit e32649b4bad90a6216d8e93cd7dd050af8ac9740

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-2026-68139
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_main.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/c698b2735613f1f35c55688bd2252f75f31c49ad
	https://git.kernel.org/stable/c/40f9a124ebbe0d60fe165fb3f87515c35b2d72f5
	https://git.kernel.org/stable/c/a60c81f168c9fe4f5d84302d1e32b717f5a8a933
	https://git.kernel.org/stable/c/e32649b4bad90a6216d8e93cd7dd050af8ac9740