lkml.org 
[lkml]   [2023]   [Jul]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.10 3/9] x86/kprobes: Retrieve correct opcode for group instruction
Date
From: Masami Hiramatsu <mhiramat@kernel.org>

[ Upstream commit d60ad3d46f1d04a282c56159f1deb675c12733fd ]

Since the opcodes start from 0xff are group5 instruction group which is
not 2 bytes opcode but the extended opcode determined by the MOD/RM byte.

The commit abd82e533d88 ("x86/kprobes: Do not decode opcode in resume_execution()")
used insn->opcode.bytes[1], but that is not correct. We have to refer
the insn->modrm.bytes[1] instead.

Fixes: abd82e533d88 ("x86/kprobes: Do not decode opcode in resume_execution()")
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/161469872400.49483.18214724458034233166.stgit@devnote2
Signed-off-by: Li Huafei <lihuafei1@huawei.com>
---
arch/x86/kernel/kprobes/core.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 19ca5164be4d..40d5c603ce8e 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -464,7 +464,11 @@ static void set_resume_flags(struct kprobe *p, struct insn *insn)
break;
#endif
case 0xff:
- opcode = insn->opcode.bytes[1];
+ /*
+ * Since the 0xff is an extended group opcode, the instruction
+ * is determined by the MOD/RM byte.
+ */
+ opcode = insn->modrm.bytes[0];
if ((opcode & 0x30) == 0x10) {
/*
* call absolute, indirect
--
2.17.1
\
 
 \ /
  Last update: 2023-07-05 08:48    [W:0.062 / U:0.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site