From ef00818c50cf55a3a56bd9a9fae867c92dfb84e7 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 f3c75809fed2..006041fbb65f 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -362,7 +362,6 @@ static bool mmio_read(int size, unsigned long addr, unsigned long *val) .r12 = size, .r13 = EPT_READ, .r14 = addr, - .r15 = *val, }; if (__tdx_hypercall_ret(&args))