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@linux.intel.com Reported-by: Sean Christopherson seanjc@google.com Fixes: 31d58c4e557d ("x86/tdx: Handle in-kernel MMIO") Cc: stable@vger.kernel.org # 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))
On 8/26/24 05:53, Kirill A. Shutemov wrote:
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.
The key to this is that 'val' is only used for the _return_ value, right?
On Mon, Aug 26, 2024 at 09:41:49AM -0700, Dave Hansen wrote:
On 8/26/24 05:53, Kirill A. Shutemov wrote:
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.
The key to this is that 'val' is only used for the _return_ value, right?
Correct.
linux-stable-mirror@lists.linaro.org
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Dave Hansen -
Kirill A. Shutemov