[PATCH v6 11/13] x86/xsaves: When a disabled xstate component offset is requested, return NULL

From: Yu-cheng Yu
Date: Tue May 10 2016 - 19:38:03 EST


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@xxxxxxxxx>
---
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 a913d4e..7c2cdc4 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