On Thu, Jun 12, 2025 at 07:46:12PM +0200, Uladzislau Rezki wrote: > On Thu, Jun 12, 2025 at 10:30:38AM -0700, Boqun Feng wrote: > > > > > > On Tue, Jun 10, 2025, at 12:33 PM, Joel Fernandes wrote: > > > On 6/10/2025 1:34 PM, Uladzislau Rezki (Sony) wrote: > > >> Currently the call_rcu() API does not check whether a callback > > >> pointer is NULL. If NULL is passed, rcu_core() will try to invoke > > >> it, resulting in NULL pointer dereference and a kernel crash. > > >> > > >> To prevent this and improve debuggability, this patch adds a check > > >> for NULL and emits a kernel stack trace to help identify a faulty > > >> caller. > > >> > > >> Signed-off-by: Uladzislau Rezki (Sony) <ure...@gmail.com> > > > > > > Reviewed-by: Joel Fernandes <joelagn...@nvidia.com> > > > > > > > Reviewed-by: Boqun Feng <boqun.f...@gmail.com> > > > Thank you for review, Boqun! > > > > I will add this first one (only this one since we're discussing the > > > others) to a > > > new rcu/fixes-for-6.16 branch, but let me know if any objections. > > > > > > > Not sure it´s urgent enough given the current evidence. > > > Let me clarify it a bit. My point is that, we get a kernel crash in a > subsystem we are responsible for, i.e. no matter if there are faulty > users of it(third party applications), the point is users can crash it. >
Fair enough. > The kernel robot reports it and it is already a strong indication that > the subsystem is not hardened against invalid inputs: > > "BUG: unable to handle kernel NULL pointer dereference in rcu_core (3)" > > so this in the rcu_core() which is part of RCU. > > But, anyway Joel should decide. I shared my opinion :) > Of course, my point is that the urgency is not high enough so we have to put it in rcu/fixes, but it's a fix, and if Joel had the time to do it, feel free. Joel's decision. Regards, Boqun > -- > Uladzislau Rezki
