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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: 14e4945426 ("libnvdimm, btt: BTT updates for UEFI 2.7 format")
Cc: <stable@vger.kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Reported-by: Maurice A. Saldivar <maurice.a.saldivar@hpe.com>
Tested-by: Maurice A. Saldivar <maurice.a.saldivar@hpe.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
This commit is contained in:
Dan Williams 2017-09-18 14:48:58 -07:00
parent 5e75fe3927
commit 33a5608671
1 changed files with 9 additions and 0 deletions
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9
drivers/nvdimm/namespace_devs.c
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@ -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;