The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x d4fc4d01471528da8a9797a065982e05090e1d81 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2024100100-emperor-thespian-397f@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

d4fc4d014715 ("x86/tdx: Fix "in-kernel MMIO" check") 859e63b789d6 ("x86/tdx: Convert shared memory back to private on kexec") 533c67e63584 ("mm/mglru: add dummy pmd_dirty()")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From d4fc4d01471528da8a9797a065982e05090e1d81 Mon Sep 17 00:00:00 2001 From: "Alexey Gladkov (Intel)" legion@kernel.org Date: Fri, 13 Sep 2024 19:05:56 +0200 Subject: [PATCH] x86/tdx: Fix "in-kernel MMIO" check

TDX only supports kernel-initiated MMIO operations. The handle_mmio() function checks if the #VE exception occurred in the kernel and rejects the operation if it did not.

However, userspace can deceive the kernel into performing MMIO on its behalf. For example, if userspace can point a syscall to an MMIO address, syscall does get_user() or put_user() on it, triggering MMIO #VE. The kernel will treat the #VE as in-kernel MMIO.

Ensure that the target MMIO address is within the kernel before decoding instruction.

Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO") Signed-off-by: Alexey Gladkov (Intel) legion@kernel.org Signed-off-by: Dave Hansen dave.hansen@linux.intel.com Reviewed-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com Acked-by: Dave Hansen dave.hansen@linux.intel.com Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/565a804b80387970460a4ebc67c88d1380f61ad1.1726237...

diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index da8b66dce0da..327c45c5013f 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -16,6 +16,7 @@ #include <asm/insn-eval.h> #include <asm/pgtable.h> #include <asm/set_memory.h> +#include <asm/traps.h>

/* MMIO direction */ #define EPT_READ 0 @@ -433,6 +434,11 @@ static int handle_mmio(struct pt_regs *regs, struct ve_info *ve) return -EINVAL; }

+ if (!fault_in_kernel_space(ve->gla)) { + WARN_ONCE(1, "Access to userspace address is not supported"); + return -EINVAL; + } + /* * Reject EPT violation #VEs that split pages. *