On Wed, 27 Jan 2021 18:08:34 +1100 Alexey Kardashevskiy <aik@xxxxxxxxx> wrote: > > I am running syzkaller and the kernel keeps crashing in > __traceiter_##_name. This patch makes these crashes happen lot less I have another solution to the above issue. But I'm now concerned with what you write below. > often (and so did the v1) but the kernel still crashes (examples below > but the common thing is that they crash in tracepoints). Disasm points > to __DO_TRACE_CALL(name) and this fixes it: > > ======================== > --- a/include/linux/tracepoint.h > +++ b/include/linux/tracepoint.h > @@ -313,6 +313,7 @@ static inline struct tracepoint > *tracepoint_ptr_deref(tracepoint_ptr_t *p) > \ > it_func_ptr = \ > > rcu_dereference_raw((&__tracepoint_##_name)->funcs); \ > + if (it_func_ptr) \ Looking at v2 of the patch, I found a bug that could make this happen. I'm looking at doing something else that doesn't affect the fast path nor does it bloat the kernel more than necessary. I'll see if I can get that patch out today. Thanks for the report. -- Steve
