On Thu, Dec 3, 2020 at 10:19 AM Dmitry Vyukov <dvyu...@google.com> wrote: > > On Thu, Dec 3, 2020 at 10:10 AM Alexey Kardashevskiy <a...@ozlabs.ru> wrote: > > > > Hi! > > > > Syzkaller triggered WARN_ON_ONCE at > > > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/kernel/tracepoint.c?h=v5.10-rc6#n266 > > > > > > === > > static int tracepoint_add_func(struct tracepoint *tp, > > struct tracepoint_func *func, int prio) > > { > > struct tracepoint_func *old, *tp_funcs; > > int ret; > > > > if (tp->regfunc && !static_key_enabled(&tp->key)) { > > ret = tp->regfunc(); > > if (ret < 0) > > return ret; > > } > > > > tp_funcs = rcu_dereference_protected(tp->funcs, > > lockdep_is_held(&tracepoints_mutex)); > > old = func_add(&tp_funcs, func, prio); > > if (IS_ERR(old)) { > > WARN_ON_ONCE(PTR_ERR(old) != -ENOMEM); > > return PTR_ERR(old); > > } > > > > === > > > > What is the common approach here? Syzkaller reacts on this as if it was > > a bug but WARN_ON_ONCE here seems intentional. Do we still push for > > removing such warnings? > > +LKML
+LKML for real > Hi Alexey, > > Yes, see the guidelines here: > https://elixir.bootlin.com/linux/v5.10-rc6/source/include/asm-generic/bug.h#L67 > > Without a criteria for kernel but/not a kernel bug no kernel testing > is possible. > > But this may be a real bug as well. The code seems to assume that > ENOMEM is the only possible error here, which is not the case in > reality. > > > > Another example is: > > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/tracepoint.h?h=v5.10-rc6#n313 > > > > My VMs crash on dereferencing it_func_ptr which is easily fixable by: > > > > @@ -307,9 +307,11 @@ static inline struct tracepoint > > *tracepoint_ptr_deref(tracepoint_ptr_t *p) > > \ > > it_func_ptr = \ > > > > rcu_dereference_raw((&__tracepoint_##_name)->funcs); \ > > + if (it_func_ptr) \ > > do { \ > > it_func = (it_func_ptr)->func; \ > > __data = (it_func_ptr)->data; \ > > > > > > But - this only happens when OOM killer starts killing syzkaller > > processes (I do not give it much memory so it is quite artificial > > environment). Do we push these? > > > > Are there guidelines of some sort? Thanks, > > > > > > -- > > Alexey > > > > -- > > You received this message because you are subscribed to the Google Groups > > "syzkaller" group. > > To unsubscribe from this group and stop receiving emails from it, send an > > email to syzkaller+unsubscr...@googlegroups.com. > > To view this discussion on the web visit > > https://groups.google.com/d/msgid/syzkaller/87f443cf-26c0-6302-edee-556045bca18a%40ozlabs.ru.
