CVE-2024-44948: x86/mtrr: Check if fixed MTRRs exist before saving them
In the Linux kernel, the following vulnerability has been resolved:
x86/mtrr: Check if fixed MTRRs exist before saving them
MTRRs have an obsolete fixed variant for fine grained caching control of the 640K-1MB region that uses separate MSRs. This fixed variant has a separate capability bit in the MTRR capability MSR.
So far all x86 CPUs which support MTRR have this separate bit set, so it went unnoticed that mtrrsavestate() does not check the capability bit before accessing the fixed MTRR MSRs.
Though on a CPU that does not support the fixed MTRR capability this results in a #GP. The #GP itself is harmless because the RDMSR fault is handled gracefully, but results in a WARNON().
Add the missing capability check to prevent this.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.135-1Fixed in 6.12.25-1Fixed in 6.12.27-1 - Upgrade
Upgrade
debian/linux-6.1to a version that resolves this vulnerability.Fixed in 6.1.129-1~deb11u1 - Compensating control
Modify x86 mtrr_save_state() to check the fixed-MTRR capability bit in the MTRR capability MSR before accessing the fixed MTRR MSRs.
Event History
Frequently Asked Questions
What is the severity of CVE-2024-44948?
CVE-2024-44948 is classified as a medium severity vulnerability.
How do I fix CVE-2024-44948?
To fix CVE-2024-44948, upgrade to the patched versions of the linux package, which are 5.10.226-1, 6.1.123-1, 6.1.119-1, 6.12.11-1, or 6.12.12-1.
What Linux distributions are affected by CVE-2024-44948?
CVE-2024-44948 affects Debian-based distributions that utilize the specified versions of the Linux kernel.
What components of the Linux kernel does CVE-2024-44948 impact?
CVE-2024-44948 impacts the x86/mtrr component of the Linux kernel related to memory type range registers.
Is there a workaround for CVE-2024-44948?
Currently, there is no known workaround for CVE-2024-44948 other than applying the appropriate kernel updates.