Debian: CVE-2021-47617: linux -- security update

Debian: CVE-2021-47617: linux -- security update

Severity

5

CVSS

(AV:L/AC:L/Au:S/C:N/I:N/A:C)

Published

06/20/2024

Created

07/31/2024

Added

07/30/2024

Modified

01/30/2025

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.

Solution(s)

• debian-upgrade-linux

References

• https://attackerkb.com/topics/cve-2021-47617
• CVE - 2021-47617