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authorAlexey Gladkov (Intel) <legion@kernel.org>2024-09-13 19:05:56 +0200
committerDave Hansen <dave.hansen@linux.intel.com>2024-09-26 09:45:04 -0700
commitd4fc4d01471528da8a9797a065982e05090e1d81 (patch)
tree17845dc5ba9842152130be041267744078ac93ea /arch/x86
parent98f7e32f20d28ec452afb208f9cffc08448a2652 (diff)
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/565a804b80387970460a4ebc67c88d1380f61ad1.1726237595.git.legion%40kernel.org
Diffstat (limited to 'arch/x86')
-rw-r--r--arch/x86/coco/tdx/tdx.c6
1 files changed, 6 insertions, 0 deletions
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.
*