Re: Crash when attaching uretprobes to processes running in Docker

Peter Zijlstra
2025-01-14T12:02:49Z

On Tue, Jan 14, 2025 at 12:01:50PM +0100, Oleg Nesterov wrote:
> On 01/14, Peter Zijlstra wrote:
> >
> > On Tue, Jan 14, 2025 at 10:22:20AM +0100, Jiri Olsa wrote:
> > >
> > > hack below seems to fix the issue, it's using rbx to signal that uretprobe
> > > syscall got executed, if not, trampoline does int3 and executes uretprobe
> > > handler in the old way
> > >
> > > unfortunately now the uretprobe trampoline size crosses the xol slot limit so
> > > will need to come up with some generic/arch code solution for that, code below
> > > is neglecting that for now
> >
> > Can't you detect the filter earlier and simply not install the
> > trampoline?
>
> Did you mean detect the filter in prepare_uretprobe() ?

Yep. Aren't syscall filters static for the duration of the task?

> The probed function can install the filter before return...

If you're running a task with dynamic syscall filtering, you get to keep
the pieces no?