Linux · Linux Kernel · CVE-2023-52499
**Name of the Vulnerable Software and Affected Versions**
Linux kernel versions prior to 6.1.55-d23900f.ppcnf-fsp2
**Description**
The issue is related to a problem in the ret from syscall function where the check for icache 44x need flush is done. When the flush is needed, the code jumps out-of-line to do the flush and then intends to jump back to continue the syscall return. However, the branch back to label 1b doesn't return to the correct location, instead branching back just prior to the return to userspace, causing bogus register values to be used by the rfi. The breakage was introduced by a commit that inadvertently removed the "1" label and reused it elsewhere.
**Recommendations**
To resolve the issue, add named local labels in the correct locations, ensuring the return label is outside the ifdef so that CONFIG PPC 47x=n compiles. Update to a version of the Linux kernel that includes the fix for the powerpc/47x syscall return crash.