Executive Summary

This vulnerability is in the Linux kernel's kexec subsystem, specifically related to the purgatory code used by kexec-tools. The purgatory code attempts to find a return address for a kjump by looking above the top of its stack, even when it is not a kjump kexec. After a fix was applied, the code no longer pushed an unused return address onto the stack in the non-kjump path, which caused the purgatory code to potentially crash when it tried to access a return address that was not there.

The vulnerability arises because the purgatory code expects a return address above the stack, but in the non-kjump path, this address might not exist, leading to a fault. The fix involved restoring the pushing of the unused return address in the non-kjump path to prevent crashes.

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Impact Analysis

This vulnerability can cause the purgatory code in kexec-tools to crash during a non-kjump kexec operation. Such a crash could disrupt the kexec process, which is used to load and boot into a new kernel without going through a full system reboot.

The impact is primarily a fault or crash in the kernel execution process, potentially leading to system instability or failure to properly switch kernels during kexec operations.

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