lkml.org 
[lkml]   [2019]   [Aug]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v2 2/3] kprobes: adjust kprobe addr for KPROBES_ON_FTRACE
Date
Hi,

On Wed, 21 Aug 2019 11:07:39 +0900 Masami Hiramatsu wrote:

>
>
> Hi Jisheng,
>
> On Tue, 20 Aug 2019 03:53:31 +0000
> Jisheng Zhang <Jisheng.Zhang@synaptics.com> wrote:
>
> > For KPROBES_ON_FTRACE case, we need to adjust the kprobe's addr
> > correspondingly.
>
> Either KPROBES_ON_FTRACE=y or not, ftrace_location() check must be
> done correctly. If it failed, kprobes can modify the instruction
> which can be modified by ftrace.
>
> >
> > Signed-off-by: Jisheng Zhang <Jisheng.Zhang@synaptics.com>
> > ---
> > kernel/kprobes.c | 10 +++++++---
> > 1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 9873fc627d61..3fd2f68644da 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -1484,15 +1484,19 @@ static inline int check_kprobe_rereg(struct kprobe *p)
> >
> > int __weak arch_check_ftrace_location(struct kprobe *p)
> > {
> > - unsigned long ftrace_addr;
> > + unsigned long ftrace_addr, addr = (unsigned long)p->addr;
> >
> > - ftrace_addr = ftrace_location((unsigned long)p->addr);
> > +#ifdef CONFIG_KPROBES_ON_FTRACE
> > + addr = ftrace_call_adjust(addr);
> > +#endif
> > + ftrace_addr = ftrace_location(addr);
>
> No, this is not right way to do. If we always need to adjust address
> before calling ftrace_location(), something wrong with ftrace_location()
> interface.
> ftrace_location(addr) must check the address is within the range which
> can be changed by ftrace. (dyn->ip <= addr <= dyn->ip+MCOUNT_INSN_SIZE)

yeah! I will try Naveen's suggestion, I.E patch kprobe_lookup_name() instead.

Thanks

>
>
> > if (ftrace_addr) {
> > #ifdef CONFIG_KPROBES_ON_FTRACE
> > /* Given address is not on the instruction boundary */
> > - if ((unsigned long)p->addr != ftrace_addr)
> > + if (addr != ftrace_addr)
> > return -EILSEQ;
> > p->flags |= KPROBE_FLAG_FTRACE;
> > + p->addr = (kprobe_opcode_t *)addr;
>
> And again, please don't change the p->addr silently.
>
> Thank you,
>
> > #else /* !CONFIG_KPROBES_ON_FTRACE */
> > return -EINVAL;
> > #endif
> > --
> > 2.23.0.rc1
> >
>
>
> --
> Masami Hiramatsu <mhiramat@kernel.org>

\
 
 \ /
  Last update: 2019-08-21 04:52    [W:0.046 / U:4.288 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site