libnvdimm, region: fix flush hint detection crash
commit bc042fdfbb92b5b13421316b4548e2d6e98eed37 upstream.
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
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Fixes: f284a4f23752 ("libnvdimm: introduce nvdimm_flush() and nvdimm_has_flush()")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c
index 9cf6f1a..f623062 100644
--- a/drivers/nvdimm/region_devs.c
+++ b/drivers/nvdimm/region_devs.c
@@ -968,17 +968,20 @@
*/
int nvdimm_has_flush(struct nd_region *nd_region)
{
- struct nd_region_data *ndrd = dev_get_drvdata(&nd_region->dev);
int i;
/* no nvdimm == flushing capability unknown */
if (nd_region->ndr_mappings == 0)
return -ENXIO;
- for (i = 0; i < nd_region->ndr_mappings; i++)
- /* flush hints present, flushing required */
- if (ndrd_get_flush_wpq(ndrd, i, 0))
+ for (i = 0; i < nd_region->ndr_mappings; i++) {
+ struct nd_mapping *nd_mapping = &nd_region->mapping[i];
+ struct nvdimm *nvdimm = nd_mapping->nvdimm;
+
+ /* flush hints present / available */
+ if (nvdimm->num_flush)
return 1;
+ }
/*
* The platform defines dimm devices without hints, assume