From bc042fdfbb92b5b13421316b4548e2d6e98eed37 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 24 Apr 2017 15:43:05 -0700 Subject: [PATCH] libnvdimm, region: fix flush hint detection crash 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 Cc: Reviewed-by: Jeff Moyer Fixes: f284a4f23752 ("libnvdimm: introduce nvdimm_flush() and nvdimm_has_flush()") Signed-off-by: Dan Williams --- drivers/nvdimm/region_devs.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/nvdimm/region_devs.c b/drivers/nvdimm/region_devs.c index 8de5a04644a1..24abceda986a 100644 --- a/drivers/nvdimm/region_devs.c +++ b/drivers/nvdimm/region_devs.c @@ -1000,17 +1000,20 @@ EXPORT_SYMBOL_GPL(nvdimm_flush); */ 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 -- 2.30.2