diff options
| author | Masami Hiramatsu <mhiramat@kernel.org> | 2021-03-03 00:25:24 +0900 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2021-03-23 16:07:55 +0100 |
| commit | d60ad3d46f1d04a282c56159f1deb675c12733fd (patch) | |
| tree | 01620096f5924701804b0739111d46209dd610ce /arch/x86/kernel/kprobes | |
| parent | 0705ef64d1ff52b817e278ca6e28095585ff31e1 (diff) | |
x86/kprobes: Retrieve correct opcode for group instruction
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
Diffstat (limited to 'arch/x86/kernel/kprobes')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 60a540fcbd56..9b31790a0b0a 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -453,7 +453,11 @@ 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 |