On 01/23/2017 01:43 AM, tip-bot for Kevin Hao wrote: > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index 1d77704..e287b90 100644 > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -1070,6 +1070,7 @@ int copyin_to_xsaves(const void *kbuf, const void > __user *ubuf, > * Add back in the features that came in from userspace: > */ > xsave->header.xfeatures |= xfeatures; > + xsave->header.xcomp_bv = XCOMP_BV_COMPACTED_FORMAT | > xsave->header.xfeatures;
FYI, this commit bit me today. If userspace happens to have bits clear in the 'xfeatures' field, this will *CLEAR* bits in xcomp_bv, changing the format of the XSAVE buffer, and breaking anything that looks at the buffer that doesn't use the instructions. Yu-cheng's dffba9a31c commit removed this line and fixed it up, but this might bite someone who is bisecting.
