linux-kernel - [PATCH 5.15 36/78] x86/vsyscall_emu/64: Dont use RET in vsyscall emulation

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Message-Id: <20220712183240.267699225@linuxfoundation.org>
Date:   Tue, 12 Jul 2022 20:39:06 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>,
        Borislav Petkov <bp@...e.de>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Subject: [PATCH 5.15 36/78] x86/vsyscall_emu/64: Dont use RET in vsyscall emulation

From: Peter Zijlstra <peterz@...radead.org>

commit 15583e514eb16744b80be85dea0774ece153177d upstream.

This is userspace code and doesn't play by the normal kernel rules.

Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Reviewed-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Borislav Petkov <bp@...e.de>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@...onical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/entry/vsyscall/vsyscall_emu_64.S |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/arch/x86/entry/vsyscall/vsyscall_emu_64.S
+++ b/arch/x86/entry/vsyscall/vsyscall_emu_64.S
@@ -19,17 +19,20 @@ __vsyscall_page:
 
 	mov $__NR_gettimeofday, %rax
 	syscall
-	RET
+	ret
+	int3
 
 	.balign 1024, 0xcc
 	mov $__NR_time, %rax
 	syscall
-	RET
+	ret
+	int3
 
 	.balign 1024, 0xcc
 	mov $__NR_getcpu, %rax
 	syscall
-	RET
+	ret
+	int3
 
 	.balign 4096, 0xcc