The mmio_read() function makes a TDVMCALL to retrieve MMIO data for an
address from the VMM.
Sean noticed that mmio_read() unintentionally exposes the value of an
initialized variable on the stack to the VMM.
Do not send the original value of *val to the VMM.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO")
Cc: stable@xxxxxxxxxxxxxxx # v5.19+
---
arch/x86/coco/tdx/tdx.c | 1 -
1 file changed, 1 deletion(-)
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 078e2bac2553..da8b66dce0da 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -389,7 +389,6 @@ static bool mmio_read(int size, unsigned long addr, unsigned long *val)
.r12 = size,
.r13 = EPT_READ,
.r14 = addr,
- .r15 = *val,
};
if (__tdx_hypercall(&args))
--
2.43.0
