CVE-2021-47276: ftrace: Do not blindly read the ip address in ftrace_bug()

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-21 · updated 2026-06-17
Weakness: CWE-706

Description

In the Linux kernel, the following vulnerability has been resolved: ftrace: Do not blindly read the ip address in ftrace_bug() It was reported that a bug on arm64 caused a bad ip address to be used for updating into a nop in ftrace_init(), but the error path (rightfully) returned -EINVAL and not -EFAULT, as the bug caused more than one error to occur. But because -EINVAL was returned, the ftrace_bug() tried to report what was at the location of the ip address, and read it directly. This caused the machine to panic, as the ip was not pointing to a valid memory address. Instead, read the ip address with copy_from_kernel_nofault() to safely access the memory, and if it faults, report that the address faulted, otherwise report what was in that location.

Affected products

Linux kernel: from 2.6.28 before 4.4.273; from 4.5 before 4.9.273; from 4.10 before 4.14.237; from 4.15 before 4.19.195; from 4.20 before 5.4.126; from 5.5 before 5.10.44 — fixed in 4.14.237, 4.19.195, 4.4.273, 4.9.273, 5.10.44, 5.12.11

How to fix

Upgrade to a fixed version: Linux kernel 4.14.237, 4.19.195, 4.4.273, 4.9.273. Check the vendor advisory for mitigations.

References

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