From 5aaee3e9ef32913ed77eb8fe4e9b51b5ace32a67 Mon Sep 17 00:00:00 2001 From: Masami Hiramatsu <mhiramat@kernel.org> Date: Wed, 9 May 2018 21:58:45 +0900 Subject: uprobes/x86: Prohibit probing on MOV SS instruction [ 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(+) diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c index 495c776de4b4..e1ea13ae53b9 100644 --- a/arch/x86/kernel/uprobes.c +++ b/arch/x86/kernel/uprobes.c @@ -296,6 +296,10 @@ static int uprobe_init_insn(struct arch_uprobe *auprobe, struct insn *insn, bool 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 -- cgit v1.2.3