Messages in this thread Patch in this message | | | From | Masami Hiramatsu <> | Subject | [PATCH -tip 2/2] x86: kprobes: Prohibit probing on instruction which has Xen prefix | Date | Wed, 4 Sep 2019 20:46:09 +0900 |
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Prohibit probing on instruction which has XEN_EMULATE_PREFIX (it must be cpuid.) Since that prefix is a marker for Xen, if we modify the marker by kprobe's int3, that doesn't work as expected.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> --- 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 43fc13c831af..b1e86af4a985 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 XEN_EMULATE_PREFIX instruction */ + if (insn_has_xen_prefix(insn)) + return 0; + /* Another subsystem puts a breakpoint, failed to recover */ if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION) return 0;
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