kernel-packages team mailing list archive

[dann frazier <dann.frazier@xxxxxxxxxxxxx>]

Public bug reported:

[Impact]
Causes fault which can lead to a hang or crash on ARM systems when loading the ipmi_si module.

The ipmi_si driver includes code that probes into iospace for a KCS
interface. This is to support platforms that don't expose this interface
in SMBIOS/ACPI tables, and this is a defined discovery mechanism as per
the IPMI Spec (v2.0r1, section 9.5).  However, this assumption is
x86-centric. It is not safe to blindly probe I/O space on ARM platforms.

[Test Case]
sudo modprobe ipmi_si

This should discover an IPMI system interface if present, or fail to
load otherwise. But it should not cause a hang, a synchronous external
abort, or other kernel failure.

[Regression Risk]
The proposed fix is only to the ARM config, so the risk to other architectures is negligible. There is a risk that there exists some system out there where this probing works - but I'm highly confident no such system exists. Existing ARM systems supported by Ubuntu either describe their IPMI/KCS interface using device-tree or do not provide one.

** Affects: linux (Ubuntu)
     Importance: High
     Assignee: dann frazier (dannf)
         Status: In Progress

** Affects: linux (Ubuntu Trusty)
     Importance: High
     Assignee: dann frazier (dannf)
         Status: In Progress

** Affects: linux (Ubuntu Utopic)
     Importance: High
     Assignee: dann frazier (dannf)
         Status: In Progress

** Affects: linux (Ubuntu Vivid)
     Importance: High
     Assignee: dann frazier (dannf)
         Status: In Progress


** Tags: hs-arm64

** Also affects: linux (Ubuntu Trusty)
   Importance: Undecided
       Status: New

** Also affects: linux (Ubuntu Vivid)
   Importance: High
     Assignee: dann frazier (dannf)
       Status: In Progress

** Also affects: linux (Ubuntu Utopic)
   Importance: Undecided
       Status: New

** Changed in: linux (Ubuntu Utopic)
       Status: New => In Progress

** Changed in: linux (Ubuntu Trusty)
       Status: New => In Progress

** Changed in: linux (Ubuntu Utopic)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Trusty)
   Importance: Undecided => High

** Changed in: linux (Ubuntu Utopic)
     Assignee: (unassigned) => dann frazier (dannf)

** Changed in: linux (Ubuntu Trusty)
     Assignee: (unassigned) => dann frazier (dannf)

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1388952

Title:
  CONFIG_IPMI_SI_PROBE_DEFAULTS should be disabled on ARM

Status in “linux” package in Ubuntu:
  In Progress
Status in “linux” source package in Trusty:
  In Progress
Status in “linux” source package in Utopic:
  In Progress
Status in “linux” source package in Vivid:
  In Progress

Bug description:
  [Impact]
  Causes fault which can lead to a hang or crash on ARM systems when loading the ipmi_si module.

  The ipmi_si driver includes code that probes into iospace for a KCS
  interface. This is to support platforms that don't expose this
  interface in SMBIOS/ACPI tables, and this is a defined discovery
  mechanism as per the IPMI Spec (v2.0r1, section 9.5).  However, this
  assumption is x86-centric. It is not safe to blindly probe I/O space
  on ARM platforms.

  [Test Case]
  sudo modprobe ipmi_si

  This should discover an IPMI system interface if present, or fail to
  load otherwise. But it should not cause a hang, a synchronous external
  abort, or other kernel failure.

  [Regression Risk]
  The proposed fix is only to the ARM config, so the risk to other architectures is negligible. There is a risk that there exists some system out there where this probing works - but I'm highly confident no such system exists. Existing ARM systems supported by Ubuntu either describe their IPMI/KCS interface using device-tree or do not provide one.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1388952/+subscriptions