[PATCH 0/2] x86/fpu: copyout_from_xsaves & copyin_to_xsaves fixes

From: riel
Date: Wed Jan 25 2017 - 21:05:44 EST

There are two issues with copyout_from_xsaves and copyin_to_xsaves.

The first is a simple bounds checking issue, where the code could
potentially clobber memory outside of a userspace buffer before it
stops copying data.

The second is more subtle. SSE and YMM XRSTOR depend on two fields
inside the legacy FP area. However, if xfeatures XFEATURE_MASK_FP is
clear, those fields do not get copied around at all. Fix that.

Thanks to Dave Hansen for helping track down that second bug.