Re: [PATCH] kretprobes: reject registration if a symbol offset is specified

[Ananth N Mavinakayanahalli]

On Tue, Feb 14, 2017 at 02:01:18PM +0530, Naveen N. Rao wrote:
> Users shouldn't be able to specify an offset with kretprobes, as we always
> want to probe at function entry. Otherwise, we won't be able to capture
> the proper return address resulting in the kretprobe never firing.
> 
> With samples/kprobes/kretprobe_example.c including an offset:
> 	my_kretprobe.kp.offset = 40;
> 
> Before this patch, the probe gets planted but never fires.
> 
> After this patch:
> 	$ sudo insmod samples/kprobes/kretprobe_example.ko
> 	[sudo] password for naveen: 
> 	insmod: ERROR: could not insert module samples/kprobes/kretprobe_example.ko: Operation not permitted
> 
> And dmesg:
> 	[48253.757629] register_kretprobe failed, returned -22
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao@xxxxxxxxxxxxxxxxxx>

Acked-by: Ananth N Mavinakayanahalli <ananth@xxxxxxxxxxxxxxxxxx>