On Wed, Apr 26, 2017 at 12:43 PM, Jeff Moyer <[email protected]> wrote: > Dan Williams <[email protected]> writes: > >> In the case where a dimm does not have any associated flush hints the >> ndrd->flush_wpq array may be uninitialized leading to crashes with the >> following signature: >> >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000010 >> IP: region_visible+0x10f/0x160 [libnvdimm] >> >> Call Trace: >> internal_create_group+0xbe/0x2f0 >> sysfs_create_groups+0x40/0x80 >> device_add+0x2d8/0x650 >> nd_async_device_register+0x12/0x40 [libnvdimm] >> async_run_entry_fn+0x39/0x170 >> process_one_work+0x212/0x6c0 >> ? process_one_work+0x197/0x6c0 >> worker_thread+0x4e/0x4a0 >> kthread+0x10c/0x140 >> ? process_one_work+0x6c0/0x6c0 >> ? kthread_create_on_node+0x60/0x60 >> ret_from_fork+0x31/0x40 > > Sorry for being dense, but I'm having a tough time connecting the dots, > here. How does region_visible trip over the missing (not uninitialized, > you're actually walking off the end of the structure) wpq_flush array?
So, you're not dense, or you're at least as equally dense as me, because I didn't immediately understand where this failure was coming from either. I just happened to trigger it while running patch2 and thought the current code just looked unsafe by inspection. > Anyway, the fix looks valid. > > Reviewed-by: Jeff Moyer <[email protected]> Thanks!
