From 33a56086712561b8b9cdc881e0317f4c36861f72 Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Mon, 18 Sep 2017 14:48:58 -0700 Subject: [PATCH] libnvdimm, namespace: fix btt claim class crash Maurice reports: BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 IP: holder_class_store+0x253/0x2b0 [libnvdimm] ...while trying to reconfigure an NVDIMM-N namespace into 'sector' / 'btt' mode. The crash points to this line: (gdb) li *(holder_class_store+0x253) 0x7773 is in holder_class_store (drivers/nvdimm/namespace_devs.c:1420). 1415 for (i = 0; i < nd_region->ndr_mappings; i++) { 1416 struct nd_mapping *nd_mapping = &nd_region->mapping[i]; 1417 struct nvdimm_drvdata *ndd = to_ndd(nd_mapping); 1418 struct nd_namespace_index *nsindex; 1419 1420 nsindex = to_namespace_index(ndd, ndd->ns_current); ...where we are failing because ndd is NULL due to NVDIMM-N dimms not supporting labels. Long story short, default to the BTTv1 format in the label-less / NVDIMM-N case. Fixes: 14e494542636 ("libnvdimm, btt: BTT updates for UEFI 2.7 format") Cc: Cc: Vishal Verma Reported-by: Maurice A. Saldivar Tested-by: Maurice A. Saldivar Signed-off-by: Dan Williams --- drivers/nvdimm/namespace_devs.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c index 1427a386a033..3e4d1e7998da 100644 --- a/drivers/nvdimm/namespace_devs.c +++ b/drivers/nvdimm/namespace_devs.c @@ -1417,6 +1417,15 @@ static int btt_claim_class(struct device *dev) struct nvdimm_drvdata *ndd = to_ndd(nd_mapping); struct nd_namespace_index *nsindex; + /* + * If any of the DIMMs do not support labels the only + * possible BTT format is v1. + */ + if (!ndd) { + loop_bitmask = 0; + break; + } + nsindex = to_namespace_index(ndd, ndd->ns_current); if (nsindex == NULL) loop_bitmask |= 1;