Re: [PATCH 2/2] kprobes: verify jprobe entry point

[Namhyung Kim <namhyung@gmail.com>]

2010-08-03 (í™”), 20:27 +0900, Masami Hiramatsu:
> Namhyung Kim wrote:
> > verify jprobe's entry point is a function entry point
> > using kallsyms' offset value.
> > 
> > Signed-off-by: Namhyung Kim <namhyung@gmail.com>
> > 
> > diff --git a/kernel/kprobes.c b/kernel/kprobes.c
> > index 8f96701..c7295f9 100644
> > --- a/kernel/kprobes.c
> > +++ b/kernel/kprobes.c
> > @@ -1334,19 +1334,25 @@ unsigned long __weak arch_deref_entry_point(void *entry)
> >  int __kprobes register_jprobes(struct jprobe **jps, int num)
> >  {
> >  	struct jprobe *jp;
> > -	int ret = 0, i;
> > +	int ret = -EINVAL, i;
> >  
> >  	if (num <= 0)
> > -		return -EINVAL;
> > +		return ret;
> >  	for (i = 0; i < num; i++) {
> >  		unsigned long addr;
> > +		unsigned long size, offset;
> > +		char namebuf[KSYM_NAME_LEN];
> > +
> 
> You need to re-initialize "ret" in each iteration,
> or "ret" will be 0 except for the 1st iteration.
> 
> >  		jp = jps[i];
> >  		addr = arch_deref_entry_point(jp->entry);
> >  
> > -		/* Todo: Verify probepoint is a function entry point */
> > -		jp->kp.pre_handler = setjmp_pre_handler;
> > -		jp->kp.break_handler = longjmp_break_handler;
> > -		ret = register_kprobe(&jp->kp);
> > +		/* Verify probepoint is a function entry point */
> > +		if (kallsyms_lookup(addr, &size, &offset, NULL, namebuf) &&
> > +		    offset = 0) {
> > +			jp->kp.pre_handler = setjmp_pre_handler;
> > +			jp->kp.break_handler = longjmp_break_handler;
> > +			ret = register_kprobe(&jp->kp);
> 
> 		because, this line assigns 0 to ret if no error.
> 
> > +		}
> 
> I think here is a good point to do that. (in else block)
> 
> >  
> >  		if (ret < 0) {
> >  			if (i > 0)
> 
> Thank you,

Thanks for reviewing.
I'll resend the fix soon after.


-- 
Regards,
Namhyung Kim


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