On Fri, Jun 9, 2023 at 2:38 AM zhangmingyi <zhangmingyi5@xxxxxxxxxx> wrote: > > On Fri, Jun 9, 2023 at 1:39 AM Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx> wrote: > > > On Thu, Jun 8, 2023 at 9:27 AM Stanislav Fomichev <sdf@xxxxxxxxxx> wrote: > > > > > > On Thu, Jun 8, 2023 at 6:00 AM zhangmingyi <zhangmingyi5@xxxxxxxxxx> wrote: > > > > > > > > On 06/06,Stanislav Fomichev wrote: > > > > > > > > > On 06/05, Xin Liu wrote: > > > > > > From: zhangmingyi <zhangmingyi5@xxxxxxxxxx> > > > > > > > > > > > The sample_cb of the ring_buffer__new interface can transfer NULL. However, > > > > > > the system does not check whether sample_cb is NULL during > > > > > > ring_buffer__poll, null pointer is used. > > > > > > > > > What is the point of calling ring_buffer__new with sample_cb == NULL? > > > > > > > > Yes, as you said, passing sample_cb in ring_buffer__new to NULL doesn't > > > > make sense, and few people use it that way, but that doesn't prevent this > > > > from being a allowed and supported scenario. And when ring_buffer__poll is > > > > called, it leads to a segmentation fault (core dump), which I think needs > > > > to be fixed to ensure the security quality of libbpf. > > > > > > I dunno. I'd argue that passing a NULL to ring_buffer__new is an API > > > misuse. Maybe ring_buffer__new should return -EINVAL instead when > > > passed NULL sample_cb? Although, we don't usually have those checks > > > for the majority of the arguments in libbpf... > > > > Right. I'd say we should add a proper doc comment specifying all > > arguments and which ones are optional or not. And make it explicit > > that callback is not optional. If we start checking every possible > > pointer for NULL, libbpf will be littered with NULL checks, I'm not > > sure that's good. > > I agree, we should add a proper doc comment specifying all > arguments and which ones are optional or not. > However, why does the external interface API in libbpf not verify input > parameters or add verification where risky operations may exist? > What's more, i think sample_cb=NULL is not strictly a mistake or > prohibited use, and is meaningless. It's not really customary in C to do it? So maybe you can follow up with the update to the doc? The kindergarten is over, you pass NULL you get SIGSEGV :-D
