Bug 2513464 (CVE-2026-68139)

Summary: CVE-2026-68139 kernel: net/mlx5e: Use sender devcom for MPV master-up
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
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Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the net/mlx5e driver within the Linux kernel. This vulnerability occurs during PCIe DPC (Downstream Port Containment) recovery when multiport affiliation events are replayed. A race condition can lead to a NULL pointer dereference if a concurrent master-up event accesses uninitialized private data. Successful exploitation of this flaw can cause a kernel panic, resulting in a Denial of Service (DoS) for the affected system.
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Description OSIDB Bzimport 2026-08-10 12:38:50 UTC 
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.
Comment 1 Mauro Matteo Cascella 2026-08-11 10:47:08 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081059-CVE-2026-68139-276e@gregkh/T