From c2ee4dfd04970f1597eea58bb30eb93e1ed5a491 Mon Sep 17 00:00:00 2001
From: Konstantin Belousov <kib@FreeBSD.org>
Date: Wed, 22 Sep 2021 00:09:34 +0300
Subject: [PATCH] ia32_get_fpcontext(): xfpusave can be legitimately NULL

Reported by:	cy
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Fixes:	bd9e0f5df681da8b5ef05
---
 sys/amd64/ia32/ia32_signal.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/sys/amd64/ia32/ia32_signal.c b/sys/amd64/ia32/ia32_signal.c
index 1ca19072a1d..ab7100f5b9f 100644
--- a/sys/amd64/ia32/ia32_signal.c
+++ b/sys/amd64/ia32/ia32_signal.c
@@ -99,6 +99,8 @@ ia32_get_fpcontext(struct thread *td, struct ia32_mcontext *mcp,
 	bcopy(get_pcb_user_save_td(td), &mcp->mc_fpstate[0],
 	    sizeof(mcp->mc_fpstate));
 	mcp->mc_fpformat = fpuformat();
+	if (xfpusave == NULL)
+		return;
 	if (!use_xsave || cpu_max_ext_state_size <= sizeof(struct savefpu)) {
 		*xfpusave_len = 0;
 		*xfpusave = NULL;