On 19/12/2024 4:14 pm, Sedat Dilek wrote:
Hi,
Linux v6.12.6 will include XEN CVE fixes from mainline.
Here, I use Debian/unstable AMD64 and the SLIM LLVM toolchain 19.1.x from kernel.org.
What does it mean in ISSUE DESCRIPTION...
Furthermore, the hypercall page has no provision for Control-flow Integrity schemes (e.g. kCFI/CET-IBT/FineIBT), and will simply malfunction in such configurations.
...when someone uses Clang-kCFI?
The hypercall page has functions of the form:
MOV $x, %eax VMCALL / VMMCALL / SYSCALL RET
There are no ENDBR instructions, and no prologue/epilogue for hash-based CFI schemes.
This is because it's code provided by Xen, not code provided by Linux.
The absence of ENDBR instructions will yield #CP when CET-IBT is active, and the absence of hash prologue/epilogue lets the function be used in a type-confused manor that CFI should have caught.
~Andrew