From: Masami Hiramatsu <mhiramat@kernel.org>
Date: Wed, 29 Mar 2017 04:56:56 +0000 (+0900)
Subject: kprobes/x86: Fix kprobe-booster not to boost far call instructions
X-Git-Tag: v4.9.89~89
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=96d0c4c4674705677ee6dbfecc468da439dadf01;p=platform%2Fkernel%2Flinux-amlogic.git

kprobes/x86: Fix kprobe-booster not to boost far call instructions


[ 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@kernel.org>
Cc: Ananth N Mavinakayanahalli <ananth@linux.vnet.ibm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ye Xiaolong <xiaolong.ye@intel.com>
Link: http://lkml.kernel.org/r/149076340615.22469.14066273186134229909.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index b55d07b9d530..808ee7f566f8 100644
--- 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;