CVE-2022-49357: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-49357 addresses a vulnerability in the Linux kernel related to UEFI Secure Boot certificate handling on Apple T2 Macs. When Linux attempts to read the db and dbx EFI variables during early boot to load UEFI Secure Boot certificates, a page fault occurs in Apple firmware code, leading to EFI runtime services being disabled (Kernel Git).

The issue manifests when the kernel tries to access UEFI variables for Secure Boot certificates, triggering a page fault in the Apple firmware code. This results in the kernel logging a warning from arch/x86/platform/efi/quirks.c and subsequently disabling EFI runtime services. The problem affects various Apple T2 Mac models including MacBookPro15,1 through MacBookPro16,4, MacBookAir8,1 through MacBookAir9,1, MacMini8,1, MacPro7,1, and iMac20,1/20,2 (Kernel Git).

When triggered, the vulnerability causes the EFI Runtime Services to be disabled, preventing proper UEFI Secure Boot certificate loading. This results in error messages including 'Couldn't get UEFI db list' and 'EFI Runtime Services are disabled!' which affects the system's secure boot functionality (NVD).

The vulnerability has been resolved by implementing a quirk that skips reading these UEFI variables on affected Apple T2 Mac models. The fix involves checking the system's DMI information and avoiding the problematic certificate loading operation on matched systems (Kernel Git).