CVE-2021-47617 PCI: pciehp: Fix infinite loop in IRQ handler upon power fault

2024-06-2010:57:01

Linux

www.cve.org

linux kernel

pci

power fault

0.0004 Low

EPSS

Percentile

10.4%

JSON

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

PCI: pciehp: Fix infinite loop in IRQ handler upon power fault

The Power Fault Detected bit in the Slot Status register differs from
all other hotplug events in that it is sticky: It can only be cleared
after turning off slot power. Per PCIe r5.0, sec. 6.7.1.8:

If a power controller detects a main power fault on the hot-plug slot,
it must automatically set its internal main power fault latch […].
The main power fault latch is cleared when software turns off power to
the hot-plug slot.

The stickiness used to cause interrupt storms and infinite loops which
were fixed in 2009 by commits 5651c48cfafe (“PCI pciehp: fix power fault
interrupt storm problem”) and 99f0169c17f3 (“PCI: pciehp: enable
software notification on empty slots”).

Unfortunately in 2020 the infinite loop issue was inadvertently
reintroduced by commit 8edf5332c393 (“PCI: pciehp: Fix MSI interrupt
race”): The hardirq handler pciehp_isr() clears the PFD bit until
pciehp’s power_fault_detected flag is set. That happens in the IRQ
thread pciehp_ist(), which never learns of the event because the hardirq
handler is stuck in an infinite loop. Fix by setting the
power_fault_detected flag already in the hardirq handler.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/pci/hotplug/pciehp_hpc.c"
    ],
    "versions": [
      {
        "version": "a8cc52270f3d",
        "lessThan": "ff27f7d0333c",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "4667358dab9c",
        "lessThan": "464da38ba827",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8edf5332c393",
        "lessThan": "3b4c966fb156",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8edf5332c393",
        "lessThan": "1db58c6584a7",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8edf5332c393",
        "lessThan": "6d6f1f0dac3e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "8edf5332c393",
        "lessThan": "23584c1ed3e1",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/pci/hotplug/pciehp_hpc.c"
    ],
    "versions": [
      {
        "version": "5.7",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.7",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.233",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.177",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.97",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.20",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16.6",
        "lessThanOrEqual": "5.16.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.17",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]