[PATCH] libnvdimm, namespace: use a safe lookup for dimm device name

From: Dan Williams
Date: Sat Apr 07 2018 - 11:00:55 EST


The following NULL dereference results from incorrectly assuming that
ndd is valid in this print:

struct nvdimm_drvdata *ndd = to_ndd(&nd_region->mapping[i]);

/*
* Give up if we don't find an instance of a uuid at each
* position (from 0 to nd_region->ndr_mappings - 1), or if we
* find a dimm with two instances of the same uuid.
*/
dev_err(&nd_region->dev, "%s missing label for %pUb\n",
dev_name(ndd->dev), nd_label->uuid);

BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
IP: nd_region_register_namespaces+0xd67/0x13c0 [libnvdimm]
PGD 0 P4D 0
Oops: 0000 [#1] SMP PTI
CPU: 43 PID: 673 Comm: kworker/u609:10 Not tainted 4.16.0-rc4+ #1
[..]
RIP: 0010:nd_region_register_namespaces+0xd67/0x13c0 [libnvdimm]
[..]
Call Trace:
? devres_add+0x2f/0x40
? devm_kmalloc+0x52/0x60
? nd_region_activate+0x9c/0x320 [libnvdimm]
nd_region_probe+0x94/0x260 [libnvdimm]
? kernfs_add_one+0xe4/0x130
nvdimm_bus_probe+0x63/0x100 [libnvdimm]

Switch to using the nvdimm device directly.

Fixes: 0e3b0d123c8f ("libnvdimm, namespace: allow multiple pmem...")
Cc: <stable@xxxxxxxxxxxxxxx>
Reported-by: Dave Jiang <dave.jiang@xxxxxxxxx>
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
---
drivers/nvdimm/namespace_devs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/nvdimm/namespace_devs.c b/drivers/nvdimm/namespace_devs.c
index 89b40ff83025..28afdd668905 100644
--- a/drivers/nvdimm/namespace_devs.c
+++ b/drivers/nvdimm/namespace_devs.c
@@ -1921,7 +1921,7 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
}

if (i < nd_region->ndr_mappings) {
- struct nvdimm_drvdata *ndd = to_ndd(&nd_region->mapping[i]);
+ struct nvdimm *nvdimm = nd_region->mapping[i].nvdimm;

/*
* Give up if we don't find an instance of a uuid at each
@@ -1929,7 +1929,7 @@ static struct device *create_namespace_pmem(struct nd_region *nd_region,
* find a dimm with two instances of the same uuid.
*/
dev_err(&nd_region->dev, "%s missing label for %pUb\n",
- dev_name(ndd->dev), nd_label->uuid);
+ nvdimm_name(nvdimm), nd_label->uuid);
rc = -EINVAL;
goto err;
}