From ed405958057ca6a8c4c9178a7a3b1167fabb45f5 Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Wed, 13 Aug 2008 11:38:14 -0700 Subject: [PATCH] x86, xsave: clear the user buffer before doing fxsave/xsave fxsave/xsave instructions will not touch all the bytes in the fxsave/xsave frame. Clear the user buffer before doing fxsave/xsave directly to user buffer during the sigcontext setup. This is essentially needed in the context of xsave(for example, some of the fields in the xsave header are not touched by the xsave and defined as must be zero). This will also present uniform and clean context to the user (from which user can safely do fxrstor/xrstor). Signed-off-by: Suresh Siddha Signed-off-by: Ingo Molnar --- arch/x86/kernel/xsave.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/kernel/xsave.c b/arch/x86/kernel/xsave.c index 7415f3e38a5..bb097b1644d 100644 --- a/arch/x86/kernel/xsave.c +++ b/arch/x86/kernel/xsave.c @@ -92,6 +92,12 @@ int save_i387_xstate(void __user *buf) return 0; clear_used_math(); /* trigger finit */ if (task_thread_info(tsk)->status & TS_USEDFPU) { + /* + * Start with clearing the user buffer. This will present a + * clean context for the bytes not touched by the fxsave/xsave. + */ + __clear_user(buf, sig_xstate_size); + if (task_thread_info(tsk)->status & TS_XSAVE) err = xsave_user(buf); else -- 2.41.1