| From foo@baz Sun Jun 17 12:07:34 CEST 2018 |
| From: Masami Hiramatsu <mhiramat@kernel.org> |
| Date: Wed, 9 May 2018 21:58:45 +0900 |
| Subject: uprobes/x86: Prohibit probing on MOV SS instruction |
| |
| From: Masami Hiramatsu <mhiramat@kernel.org> |
| |
| [ Upstream commit 13ebe18c94f5b0665c01ae7fad2717ae959f4212 ] |
| |
| Since MOV SS and POP SS instructions will delay the exceptions until the |
| next instruction is executed, single-stepping on it by uprobes must be |
| prohibited. |
| |
| uprobe already rejects probing on POP SS (0x1f), but allows probing on MOV |
| SS (0x8e and reg == 2). This checks the target instruction and if it is |
| MOV SS or POP SS, returns -ENOTSUPP to reject probing. |
| |
| Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> |
| Signed-off-by: Thomas Gleixner <tglx@linutronix.de> |
| Acked-by: Oleg Nesterov <oleg@redhat.com> |
| Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com> |
| Cc: Francis Deslauriers <francis.deslauriers@efficios.com> |
| Cc: Alexei Starovoitov <ast@kernel.org> |
| Cc: Steven Rostedt <rostedt@goodmis.org> |
| Cc: Andy Lutomirski <luto@kernel.org> |
| Cc: "H . Peter Anvin" <hpa@zytor.com> |
| Cc: Yonghong Song <yhs@fb.com> |
| Cc: Borislav Petkov <bp@suse.de> |
| Cc: Linus Torvalds <torvalds@linux-foundation.org> |
| Cc: "David S . Miller" <davem@davemloft.net> |
| Link: https://lkml.kernel.org/r/152587072544.17316.5950935243917346341.stgit@devbox |
| Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| arch/x86/kernel/uprobes.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| --- a/arch/x86/kernel/uprobes.c |
| +++ b/arch/x86/kernel/uprobes.c |
| @@ -299,6 +299,10 @@ static int uprobe_init_insn(struct arch_ |
| if (is_prefix_bad(insn)) |
| return -ENOTSUPP; |
| |
| + /* We should not singlestep on the exception masking instructions */ |
| + if (insn_masking_exception(insn)) |
| + return -ENOTSUPP; |
| + |
| if (x86_64) |
| good_insns = good_insns_64; |
| else |