On Fri, Aug 28, 2020 at 01:11:15PM +0000, [email protected] wrote: > > -----Original Message----- > > From: Peter Zijlstra <[email protected]> > > Sent: Friday, August 28, 2020 12:13 AM > > To: [email protected]; [email protected] > > Cc: Eddy Wu (RD-TW) <[email protected]>; [email protected]; > > [email protected]; [email protected]; > > [email protected]; [email protected]; > > [email protected]; [email protected]; > > [email protected]; [email protected]; [email protected]; [email protected] > > Subject: [RFC][PATCH 3/7] kprobes: Remove kretprobe hash > > > > @@ -1935,71 +1932,45 @@ unsigned long __kretprobe_trampoline_han > > unsigned long trampoline_address, > > void *frame_pointer) > > { > > // ... removed > > // NULL here > > + first = node = current->kretprobe_instances.first; > > + while (node) { > > + ri = container_of(node, struct kretprobe_instance, llist); > > > > - orig_ret_address = (unsigned long)ri->ret_addr; > > - if (skipped) > > - pr_warn("%ps must be blacklisted because of > > incorrect kretprobe order\n", > > - ri->rp->kp.addr); > > + BUG_ON(ri->fp != frame_pointer); > > > > - if (orig_ret_address != trampoline_address) > > + orig_ret_address = (unsigned long)ri->ret_addr; > > + if (orig_ret_address != trampoline_address) { > > /* > > * This is the real return address. Any other > > * instances associated with this task are for > > * other calls deeper on the call stack > > */ > > break; > > + } > > + > > + node = node->next; > > } > > > > Hi, I found a NULL pointer dereference here, where > current->kretprobe_instances.first == NULL in these two scenario:
Hurmph, that would mean hitting the trampoline and not having a kretprobe_instance, weird. Let me try and reproduce.
