linux-kernel - [PATCH 4.9 152/241] kprobes/x86: Fix kprobe-booster not to boost far call instructions

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Message-Id: <20180319180757.472270630@linuxfoundation.org>
Date:   Mon, 19 Mar 2018 19:06:57 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Masami Hiramatsu <mhiramat@...nel.org>,
        Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        Borislav Petkov <bp@...en8.de>,
        Brian Gerst <brgerst@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Denys Vlasenko <dvlasenk@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ye Xiaolong <xiaolong.ye@...el.com>,
        Ingo Molnar <mingo@...nel.org>,
        Sasha Levin <alexander.levin@...rosoft.com>
Subject: [PATCH 4.9 152/241] kprobes/x86: Fix kprobe-booster not to boost far call instructions

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Masami Hiramatsu <mhiramat@...nel.org>


[ Upstream commit bd0b90676c30fe640e7ead919b3e38846ac88ab7 ]

Fix the kprobe-booster not to boost far call instruction,
because a call may store the address in the single-step
execution buffer to the stack, which should be modified
after single stepping.

Currently, this instruction will be filtered as not
boostable in resume_execution(), so this is not a
critical issue.

Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
Cc: Ananth N Mavinakayanahalli <ananth@...ux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Brian Gerst <brgerst@...il.com>
Cc: David S . Miller <davem@...emloft.net>
Cc: Denys Vlasenko <dvlasenk@...hat.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Josh Poimboeuf <jpoimboe@...hat.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ye Xiaolong <xiaolong.ye@...el.com>
Link: http://lkml.kernel.org/r/149076340615.22469.14066273186134229909.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kernel/kprobes/core.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -199,6 +199,8 @@ retry:
 		return (opcode != 0x62 && opcode != 0x67);
 	case 0x70:
 		return 0; /* can't boost conditional jump */
+	case 0x90:
+		return opcode != 0x9a;	/* can't boost call far */
 	case 0xc0:
 		/* can't boost software-interruptions */
 		return (0xc1 < opcode && opcode < 0xcc) || opcode == 0xcf;