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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	Rodrigo Branco <bsdaemon@google.com>,
	"Borislav Petkov (AMD)" <bp@alien8.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: [PATCH 5.10 760/783] x86/bugs: Flush IBP in ib_prctl_set()
Date: Thu, 12 Jan 2023 14:57:56 +0100
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From: Rodrigo Branco <bsdaemon@google.com>

commit a664ec9158eeddd75121d39c9a0758016097fa96 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/kernel/cpu/bugs.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1896,6 +1896,8 @@ static int ib_prctl_set(struct task_stru
 		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;