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| author | Masami Hiramatsu <mhiramat@kernel.org> | 2018-05-09 15:58:15 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2018-05-13 20:52:55 +0300 |
| commit | ee6a7354a3629f9b65bc18dbe393503e9440d6f5 (patch) | |
| tree | f12478e840fccf8f714f9315326065d440b46b7e /arch/x86/kernel/kprobes | |
| parent | a466ef76b815b86748d9870ef2a430af7b39c710 (diff) | |
| download | linux-ee6a7354a3629f9b65bc18dbe393503e9440d6f5.tar.xz | |
kprobes/x86: Prohibit probing on exception masking instructions
Since MOV SS and POP SS instructions will delay the exceptions until the
next instruction is executed, single-stepping on it by kprobes must be
prohibited.
However, kprobes usually executes those instructions directly on trampoline
buffer (a.k.a. kprobe-booster), except for the kprobes which has
post_handler. Thus if kprobe user probes MOV SS with post_handler, it will
do single-stepping on the MOV SS.
This means it is safe that if it is used via ftrace or perf/bpf since those
don't use the post_handler.
Anyway, since the stack switching is a rare case, it is safer just
rejecting kprobes on such instructions.
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Cc: Francis Deslauriers <francis.deslauriers@efficios.com>
Cc: Oleg Nesterov <oleg@redhat.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/152587069574.17316.3311695234863248641.stgit@devbox
Diffstat (limited to 'arch/x86/kernel/kprobes')
| -rw-r--r-- | arch/x86/kernel/kprobes/core.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c index 0715f827607c..6f4d42377fe5 100644 --- a/arch/x86/kernel/kprobes/core.c +++ b/arch/x86/kernel/kprobes/core.c @@ -370,6 +370,10 @@ int __copy_instruction(u8 *dest, u8 *src, u8 *real, struct insn *insn) if (insn->opcode.bytes[0] == BREAKPOINT_INSTRUCTION) return 0; + /* We should not singlestep on the exception masking instructions */ + if (insn_masking_exception(insn)) + return 0; + #ifdef CONFIG_X86_64 /* Only x86_64 has RIP relative instructions */ if (insn_rip_relative(insn)) { |