On Fri, Dec 20, 2024 at 12:26 AM Andrew Cooper andrew.cooper3@citrix.com wrote:
On 19/12/2024 11:10 pm, Sedat Dilek wrote:
On Thu, Dec 19, 2024 at 6:07 PM Sedat Dilek sedat.dilek@gmail.com wrote:
On Thu, Dec 19, 2024 at 5:44 PM Andrew Cooper andrew.cooper3@citrix.com wrote:
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 $x, %eax VMCALL / VMMCALL / SYSCALL RETThere are no ENDBR instructions, and no prologue/epilogue for hash-based CFI schemes.
This is because it's code provided by Xen, not code provided by Linux.
The absence of ENDBR instructions will yield #CP when CET-IBT is active, and the absence of hash prologue/epilogue lets the function be used in a type-confused manor that CFI should have caught.
~Andrew
Thanks for the technical explanation, Andrew.
Hope that helps the folks of "CLANG CONTROL FLOW INTEGRITY SUPPORT".
I am not an active user of XEN in the Linux-kernel but I am willing to test when Linux v6.12.6 is officially released and give feedback.
https://wiki.xenproject.org/wiki/Testing_Xen#Presence_test https://wiki.xenproject.org/wiki/Testing_Xen#Commands_for_presence_testing
# apt install -t unstable xen-utils-4.17 -y
# xl list Name ID Mem VCPUs State Time(s) Domain-0 0 7872 4 r----- 398.2
Some basic tests LGTM - see also attached stuff.
If you have any tests to recommend, let me know.
That itself is good enough as a smoke test. Thankyou for trying it out.
If you want something a bit more thorough, try https://xenbits.xen.org/docs/xtf/ (Xen's self-tests)
Grab and build it, and `./xtf-runner -aqq --host` will run a variety of extra codepaths in dom0, without the effort of making/running full guests.
~Andrew
Run on Debian 6.12.5 and my selfmade 6.12.5 and 6.12.6. All tests lead to a reboot in case of Debian or in my kernels to a shutdown.
Can you recommend a specific test?
dileks@iniza:~/src/xtf/git$ sudo ./xtf-runner --list functional xsa | grep xsa-4 test-pv64-xsa-444 test-hvm64-xsa-451 test-hvm64-xsa-454
Is there no xsa-466 test?
Thanks.
BR, -Sedat-