lkml.org 
[lkml]   [2019]   [Oct]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip: x86/core] x86: kprobes: Prohibit probing on instruction which has emulate prefix
The following commit has been merged into the x86/core branch of tip:

Commit-ID: 004e8dce9c5595697951f7cd0e9f66b35c92265e
Gitweb: https://git.kernel.org/tip/004e8dce9c5595697951f7cd0e9f66b35c92265e
Author: Masami Hiramatsu <mhiramat@kernel.org>
AuthorDate: Fri, 06 Sep 2019 22:14:20 +09:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Thu, 17 Oct 2019 21:31:57 +02:00

x86: kprobes: Prohibit probing on instruction which has emulate prefix

Prohibit probing on instruction which has XEN_EMULATE_PREFIX
or KVM's emulate prefix. Since that prefix is a marker for Xen
and KVM, if we modify the marker by kprobe's int3, that doesn't
work as expected.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Juergen Gross <jgross@suse.com>
Cc: x86@kernel.org
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: xen-devel@lists.xenproject.org
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lkml.kernel.org/r/156777566048.25081.6296162369492175325.stgit@devnote2
---
arch/x86/kernel/kprobes/core.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c
index 43fc13c..4f13af7 100644
--- a/arch/x86/kernel/kprobes/core.c
+++ b/arch/x86/kernel/kprobes/core.c
@@ -351,6 +351,10 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn)
kernel_insn_init(insn, dest, MAX_INSN_SIZE);
insn_get_length(insn);

+ /* We can not probe force emulate prefixed instruction */
+ if (insn_has_emulate_prefix(insn))
+ return 0;
+
/* Another subsystem puts a breakpoint, failed to recover */
if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION)
return 0;
\
 
 \ /
  Last update: 2019-10-18 14:49    [W:0.081 / U:6.492 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site