From d4fc4d01471528da8a9797a065982e05090e1d81 Mon Sep 17 00:00:00 2001 From: "Alexey Gladkov (Intel)" 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) Signed-off-by: Dave Hansen Reviewed-by: Kirill A. Shutemov Acked-by: Dave Hansen Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/565a804b80387970460a4ebc67c88d1380f61ad1.1726237595.git.legion%40kernel.org --- arch/x86/coco/tdx/tdx.c | 6 ++++++ 1 file changed, 6 insertions(+) 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 #include #include +#include /* 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. *