Re: [PATCH] libnvdimm: Add a NULL entry to 'nvdimm_firmware_attributes'

["Verma, Vishal L" <vishal.l.verma@intel.com>]

On Fri, 2020-08-14 at 10:10 -0700, Ira Weiny wrote:
> On Fri, Aug 14, 2020 at 08:35:09PM +0530, Vaibhav Jain wrote:
> > We recently discovered a kernel oops with 'papr_scm' module while
> > booting ppc64 phyp guest with following back-trace:
> > 
> > BUG: Kernel NULL pointer dereference on write at 0x00000188
> > Faulting instruction address: 0xc0000000005d7084
> > Oops: Kernel access of bad area, sig: 11 [#1]
> > <snip>
> > Call Trace:
> >  internal_create_group+0x128/0x4c0 (unreliable)
> >  internal_create_groups.part.4+0x70/0x130
> >  device_add+0x458/0x9c0
> >  nd_async_device_register+0x28/0xa0 [libnvdimm]
> >  async_run_entry_fn+0x78/0x1f0
> >  process_one_work+0x2c0/0x5b0
> >  worker_thread+0x88/0x650
> >  kthread+0x1a8/0x1b0
> >  ret_from_kernel_thread+0x5c/0x6c
> > 
> > A bisect lead to the 'commit 48001ea50d17f ("PM, libnvdimm: Add runtime
> > firmware activation support")' and on investigation discovered that
> > the newly introduced 'struct attribute *nvdimm_firmware_attributes[]'
> > is missing a terminating NULL entry in the array. This causes a loop
> > in sysfs's 'create_files()' to read garbage beyond bounds of
> > 'nvdimm_firmware_attributes' and trigger the oops.
> > 
> > Fixes: 48001ea50d17f ("PM, libnvdimm: Add runtime firmware activation support")
> > Reported-by: Sandipan Das <sandipan@linux.ibm.com>
> > Signed-off-by: Vaibhav Jain <vaibhav@linux.ibm.com>
> 
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>

Thanks Vaibhav and Ira. I see this was also reported and fixed by Zqiang
a couple days ago. I'll pick that, merge these trailers and add it to
the fixes queue.

> 
> > ---
> >  drivers/nvdimm/dimm_devs.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
> > index 61374def51555..b59032e0859b7 100644
> > --- a/drivers/nvdimm/dimm_devs.c
> > +++ b/drivers/nvdimm/dimm_devs.c
> > @@ -529,6 +529,7 @@ static DEVICE_ATTR_ADMIN_RW(activate);
> >  static struct attribute *nvdimm_firmware_attributes[] = {
> >  	&dev_attr_activate.attr,
> >  	&dev_attr_result.attr,
> > +	NULL,
> >  };
> >  
> >  static umode_t nvdimm_firmware_visible(struct kobject *kobj, struct attribute *a, int n)
> > -- 
> > 2.26.2
> > 
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