CVE-2021-47276: 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 ...

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.

Metrics

CVSS 3.1

5.5/10

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS Probability

0.24%

14.5th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-706

Affected Software

Vendor	Product	Versions	Update
Linux	Linux Kernel	>= 2.6.28, < 4.4.273	—
Linux	Linux Kernel	>= 4.5, < 4.9.273	—
Linux	Linux Kernel	>= 4.10, < 4.14.237	—
Linux	Linux Kernel	>= 4.15, < 4.19.195	—
Linux	Linux Kernel	>= 4.20, < 5.4.126	—
Linux	Linux Kernel	>= 5.5, < 5.10.44	—
Linux	Linux Kernel	>= 5.11, < 5.12.11	—
Linux	Linux Kernel	5.13	Rc1

References

Timeline

Published: May 21, 2024
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-47276?

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.

How severe is CVE-2021-47276?

CVE-2021-47276 has a CVSS score of 5.5/10 (MEDIUM severity). The EPSS model estimates a 0.24% probability of exploitation in the next 30 days.

How do I fix CVE-2021-47276?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.