2018-07-24 13:42:00

by Gustavo A. R. Silva

Subject: [PATCH] libnvdimm: fix NULL pointer dereference

ndd is being dereferenced before it is null checked, hence there is a
potential null pointer dereference.

Fix this by moving the pointer dereference after ndd has been properly
null checked at line 554: if (!ndd)

Addresses-Coverity-ID: 1472020 ("Dereference before null check")
Fixes: 42218e643bd2 ("libnvdimm: Use max contiguous area for namespace size")
Signed-off-by: Gustavo A. R. Silva <[email protected]>
---
drivers/nvdimm/dimm_devs.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c
index 9e977cb..1dc3125 100644
--- a/drivers/nvdimm/dimm_devs.c
+++ b/drivers/nvdimm/dimm_devs.c
@@ -546,7 +546,7 @@ resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
struct nd_mapping *nd_mapping)
{
struct nvdimm_drvdata *ndd = to_ndd(nd_mapping);
- struct nvdimm_bus *nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
+ struct nvdimm_bus *nvdimm_bus;
resource_size_t max = 0;
struct resource *res;

@@ -554,6 +554,8 @@ resource_size_t nd_pmem_max_contiguous_dpa(struct nd_region *nd_region,
if (!ndd)
return 0;

+ nvdimm_bus = walk_to_nvdimm_bus(ndd->dev);
+
if (reserve_free_pmem(nvdimm_bus, nd_mapping))
return 0;
for_each_dpa_resource(ndd, res) {
--
2.7.4

2018-07-24 19:48:50

by Keith Busch

Subject: Re: [PATCH] libnvdimm: fix NULL pointer dereference

On Tue, Jul 24, 2018 at 08:40:06AM -0500, Gustavo A. R. Silva wrote:
> ndd is being dereferenced before it is null checked, hence there is a
> potential null pointer dereference.
>
> Fix this by moving the pointer dereference after ndd has been properly
> null checked at line 554: if (!ndd)

I'll fold this into v4 of the patch since Vishal found an issue when a
DIMM has multiple regions.