[PATCH v7 11/13] x86/xsaves: When a disabled xstate component address is requested, return NULL

[Yu-cheng Yu <yu-cheng.yu@intel.com>]

It is an error to request a disabled XSAVE/XSAVES component address.
For that case, make __raw_xsave_addr() return a NULL and issue a
warning.

Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com>
Reviewed-by: Dave Hansen <dave.hansen@intel.com>
---
 arch/x86/kernel/fpu/xstate.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index 27511bb..13c6fea 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -761,6 +761,11 @@ void *__raw_xsave_addr(struct xregs_state *xsave, int xstate_feature_mask)
 {
 	int feature_nr = fls64(xstate_feature_mask) - 1;
 
+	if (!xfeature_enabled(feature_nr)) {
+		WARN_ON_FPU(1);
+		return NULL;
+	}
+
 	return (void *)xsave + xstate_comp_offsets[feature_nr];
 }
 
-- 
1.9.1