x86/fpu: Copy the full state_header in copy_kernel_to_xstate()

This is in preparation to verify the full xstate header as supplied by user-space.

Signed-off-by: Eric Biggers <[email protected]>
Cc: Andrew Morton <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Borislav Petkov <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Dmitry Vyukov <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Fenghua Yu <[email protected]>
Cc: Kees Cook <[email protected]>
Cc: Kevin Hao <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Michael Halcrow <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Wanpeng Li <[email protected]>
Cc: Yu-cheng Yu <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>

1 files changed, 4 insertions, 2 deletions

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 2427aeea33b5..02591b96bb25 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -1148,11 +1148,13 @@ int copy_kernel_to_xstate(struct xregs_state *xsave, const void *kbuf)
 	int i;
 	u64 xfeatures;
 	u64 allowed_features;
+	struct xstate_header hdr;
 
 	offset = offsetof(struct xregs_state, header);
-	size = sizeof(xfeatures);
+	size = sizeof(hdr);
 
-	memcpy(&xfeatures, kbuf + offset, size);
+	memcpy(&hdr, kbuf + offset, size);
+	xfeatures = hdr.xfeatures;
 
 	/*
 	 * Reject if the user sets any disabled or supervisor features: