From: Andrew Cooper <andrew.cooper3@citrix.com>
To: sedat.dilek@gmail.com, Juergen Gross <jgross@suse.com>,
Peter Zijlstra <peterz@infradead.org>,
Sami Tolvanen <samitolvanen@google.com>
Cc: Jan Beulich <jbeulich@suse.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Sasha Levin <sashal@kernel.org>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Kees Cook <kees@kernel.org>,
Nathan Chancellor <nathan@kernel.org>,
llvm@lists.linux.dev
Subject: Re: [Linux-6.12.y] XEN: CVE-2024-53241 / XSA-466 and Clang-kCFI
Date: Thu, 19 Dec 2024 16:44:10 +0000 [thread overview]
Message-ID: <099d3a80-4fdb-49a7-9fd0-207d7386551f@citrix.com> (raw)
In-Reply-To: <CA+icZUWHU=oXOEj5wHTzxrw_wj1w5hTvqq8Ry400s0ZCJjTEZw@mail.gmail.com>
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
next prev parent reply other threads:[~2024-12-19 16:44 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-12-19 16:14 [Linux-6.12.y] XEN: CVE-2024-53241 / XSA-466 and Clang-kCFI Sedat Dilek
2024-12-19 16:36 ` Greg Kroah-Hartman
2024-12-19 16:44 ` Andrew Cooper [this message]
2024-12-19 17:07 ` Sedat Dilek
2024-12-19 23:10 ` Sedat Dilek
2024-12-19 23:26 ` Andrew Cooper
2024-12-20 0:27 ` Sedat Dilek
2024-12-20 1:39 ` Andrew Cooper
2024-12-21 17:06 ` Sedat Dilek
2024-12-21 18:17 ` Sedat Dilek
2024-12-21 18:25 ` Sedat Dilek
2024-12-21 19:09 ` Sedat Dilek
2024-12-21 21:31 ` Andrew Cooper
2024-12-22 10:37 ` Sedat Dilek
2024-12-24 16:23 ` Sedat Dilek
2024-12-24 21:56 ` Sedat Dilek
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