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

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commit 004e8dce9c upstream.

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
Signed-off-by: Maximilian Heyne <mheyne@amazon.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Masami Hiramatsu 2019-09-06 22:14:20 +09:00 committed by Greg Kroah-Hartman
parent 6af6427a96
commit c1bdf1e6e7
1 changed files with 4 additions and 0 deletions
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4
arch/x86/kernel/kprobes/core.c
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@ -358,6 +358,10 @@ 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;