Messages in this thread | | | Date | Fri, 20 Feb 2015 11:19:25 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/2] kprobes/x86: Check for invalid ftrace location in __recover_probed_insn() |
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* Petr Mladek <pmladek@suse.cz> wrote:
> __recover_probed_insn() should always be called from an address where > an instructions starts. The check for ftrace_location() might help to > discover a potential inconsistency. Something goes terribly wrong when > an address inside the ftrace location is checked. Let's BUG() in this case. > > Suggested-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > Signed-off-by: Petr Mladek <pmladek@suse.cz> > Acked-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> > --- > arch/x86/kernel/kprobes/core.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kernel/kprobes/core.c b/arch/x86/kernel/kprobes/core.c > index 2f464b56766a..124577dcf768 100644 > --- a/arch/x86/kernel/kprobes/core.c > +++ b/arch/x86/kernel/kprobes/core.c > @@ -228,6 +228,12 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) > kp = get_kprobe((void *)addr); > faddr = ftrace_location(addr); > /* > + * Addresses inside the ftrace location are refused by > + * arch_check_ftrace_location(). Something went terribly wrong > + * if such an address is checked here. > + */ > + BUG_ON(faddr && faddr != addr);
Crashing the system with a BUG_ON() makes users very sad. Please use a construct like:
if (WARN_ON(faddr && faddr != addr)) return gently;
I've picked up your first patch.
Thanks,
Ingo
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