From 641d3e375f984db933af7fd52702181dcae27620 Mon Sep 17 00:00:00 2001
From: Rodrigo Branco <bsdaemon@google.com>
Date: Thu, 9 Feb 2023 15:10:32 -0500
Subject: [PATCH] x86/bugs: Flush IBP in ib_prctl_set()

We missed the window between the TIF flag update and the next reschedule.

Signed-off-by: Rodrigo Branco <bsdaemon@google.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
(cherry picked from commit a664ec9158eeddd75121d39c9a0758016097fa96)
CVE-2023-0045
Signed-off-by: Yuxuan Luo <yuxuan.luo@canonical.com>
Signed-off-by: Timo Aaltonen <timo.aaltonen@canonical.com>
---
 arch/x86/kernel/cpu/bugs.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 2a21046846b6f..a0778e04d1f00 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1535,6 +1535,8 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
 		if (ctrl == PR_SPEC_FORCE_DISABLE)
 			task_set_spec_ib_force_disable(task);
 		task_update_spec_tif(task);
+		if (task == current)
+			indirect_branch_prediction_barrier();
 		break;
 	default:
 		return -ERANGE;