Loop with Unreachable Exit Condition ('Infinite Loop') Affecting kernel-rt package, versions *
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Test your applications- Snyk ID SNYK-CENTOS7-KERNELRT-7294286
- published 20 Jun 2024
- disclosed 20 Jun 2024
Introduced: 20 Jun 2024
CVE-2021-47617 Open this link in a new tabHow to fix?
There is no fixed version for Centos:7 kernel-rt.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-rt package and not the kernel-rt package as distributed by Centos.
See How to fix? for Centos:7 relevant fixed versions and status.
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.
References
- https://access.redhat.com/security/cve/CVE-2021-47617
- https://git.kernel.org/stable/c/1db58c6584a72102e98af2e600ea184ddaf2b8af
- https://git.kernel.org/stable/c/23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12
- https://git.kernel.org/stable/c/3b4c966fb156ff3e70b2526d964952ff7c1574d9
- https://git.kernel.org/stable/c/464da38ba827f670deac6500a1de9a4f0f44c41d
- https://git.kernel.org/stable/c/6d6f1f0dac3e3441ecdb1103d4efb11b9ed24dd5
- https://git.kernel.org/stable/c/ff27f7d0333cff89ec85c419f431aca1b38fb16a