CVE-2021-47617
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…
Does this matter?
Lower severity and a low EPSS score (0.21%). Track it; it rarely justifies an emergency change on its own.
Description
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.
- CVSS 3.1
- 5.5 MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- EPSS
- 0.21% probability · 11th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-835
- Affected
- linux/linux kernel
- Source
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
References
- https://git.kernel.org/stable/c/1db58c6584a72102e98af2e600ea184ddaf2b8afPatch
- https://git.kernel.org/stable/c/23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12Patch
- https://git.kernel.org/stable/c/3b4c966fb156ff3e70b2526d964952ff7c1574d9Patch
- https://git.kernel.org/stable/c/464da38ba827f670deac6500a1de9a4f0f44c41dPatch
- https://git.kernel.org/stable/c/6d6f1f0dac3e3441ecdb1103d4efb11b9ed24dd5Patch
- https://git.kernel.org/stable/c/ff27f7d0333cff89ec85c419f431aca1b38fb16aPatch
- https://git.kernel.org/stable/c/1db58c6584a72102e98af2e600ea184ddaf2b8afPatch
- https://git.kernel.org/stable/c/23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12Patch
- https://git.kernel.org/stable/c/3b4c966fb156ff3e70b2526d964952ff7c1574d9Patch
- https://git.kernel.org/stable/c/464da38ba827f670deac6500a1de9a4f0f44c41dPatch
- https://git.kernel.org/stable/c/6d6f1f0dac3e3441ecdb1103d4efb11b9ed24dd5Patch
- https://git.kernel.org/stable/c/ff27f7d0333cff89ec85c419f431aca1b38fb16aPatch
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.