From: Kirill A. Shutemov Date: Mon, 26 Aug 2024 12:53:04 +0000 (+0300) Subject: x86/tdx: Fix data leak in mmio_read() X-Git-Tag: v6.11-rc7~44^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=b6fb565a2d15277896583d471b21bc14a0c99661;p=thirdparty%2Fkernel%2Flinux.git x86/tdx: Fix data leak in mmio_read() 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 --- diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index 078e2bac25531..da8b66dce0da5 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))