From 26c6af49d26ffc377e392e30d4086db19eed0ef7 Mon Sep 17 00:00:00 2001 From: "Kirill A. Shutemov" Date: Mon, 26 Aug 2024 15:53:04 +0300 Subject: [PATCH] x86/tdx: Fix data leak in mmio_read() commit b6fb565a2d15277896583d471b21bc14a0c99661 upstream. 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 (val) on the stack to the VMM. This variable is only needed as an output value. It did not need to be passed to the VMM in the first place. Do not send the original value of *val to the VMM. [ dhansen: clarify what 'val' is used for. ] Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO") Reported-by: Sean Christopherson Signed-off-by: Kirill A. Shutemov Signed-off-by: Dave Hansen Cc:stable@vger.kernel.org Link: https://lore.kernel.org/all/20240826125304.1566719-1-kirill.shutemov%40linux.intel.com Signed-off-by: Greg Kroah-Hartman --- 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 4692450aeb4d..b9da467bd222 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -328,7 +328,6 @@ 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, TDX_HCALL_HAS_OUTPUT))