[PATCH 04/10] x86/fpu: Copy the full state_header in copy_kernel_to_xstate()

[Ingo Molnar]

From: Eric Biggers <ebigg...@google.com>

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

Signed-off-by: Eric Biggers <ebigg...@google.com>
Cc: Andy Lutomirski <l...@kernel.org>
Cc: Dave Hansen <dave.han...@linux.intel.com>
Cc: Dmitry Vyukov <dvyu...@google.com>
Cc: Fenghua Yu <fenghua...@intel.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Kevin Hao <haoke...@gmail.com>
Cc: Linus Torvalds <torva...@linux-foundation.org>
Cc: Michael Halcrow <mhalc...@google.com>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Rik van Riel <r...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Wanpeng Li <wanpeng...@hotmail.com>
Cc: Yu-cheng Yu <yu-cheng...@intel.com>
Cc: kernel-harden...@lists.openwall.com
Signed-off-by: Ingo Molnar <mi...@kernel.org>
---
 arch/x86/kernel/fpu/xstate.c | 6 ++++--
 1 file 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:
-- 
2.11.0