CVE-2024-44948

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 mtrr_save_state() 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 WARN_ON(). Add the missing capability check to prevent this.

• linux linux kernel (>= 2.6.22 < 4.19.320) • linux linux kernel (>= 4.20 < 5.4.282) • linux linux kernel (>= 5.5 < 5.10.224) • linux linux kernel (>= 5.11 < 5.15.165) • linux linux kernel (>= 5.16 < 6.1.105) • linux linux kernel (>= 6.2 < 6.6.46) • linux linux kernel (>= 6.7 < 6.10.5) • linux linux kernel 6.11