From 5662c705390277536e6fc1e684c86220d7b837ea 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 BugLink: https://bugs.launchpad.net/bugs/2089340 commit d4fc4d01471528da8a9797a065982e05090e1d81 upstream. 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 Signed-off-by: Alexey Gladkov (Intel) Signed-off-by: Greg Kroah-Hartman Signed-off-by: Portia Stephens Signed-off-by: Stefan Bader --- 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 8fe4c2b07128..cc39f5492da6 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -14,6 +14,7 @@ #include #include #include +#include /* MMIO direction */ #define EPT_READ 0 @@ -429,6 +430,11 @@ 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. *