[PATCH] nvdimm: Add check for devm_kmalloc() and fix NULL pointer dereference in nd_pfn_probe() and nd_dax_probe()

[Zhaoyang Yu]

The devm_kmalloc() function may return NULL when memory allocation fails.
In nd_pfn_probe() and nd_dax_probe(), the return values of devm_kmalloc()
are not checked. If pfn_sb is NULL, it will cause a NULL pointer
dereference in the subsequent calls to nd_pfn_validate().

Additionally, if the allocation fails, the devices initialized by
nd_pfn_devinit() or nd_dax_devinit() are not properly released, leading
to memory leaks.

Fix this by checking the return value of devm_kmalloc() in both functions.
If the allocation fails, use put_device() to release the initialized device
and return -ENOMEM.

Signed-off-by: Zhaoyang Yu <2426767509@xxxxxx>
---
 drivers/nvdimm/dax_devs.c | 4 ++++
 drivers/nvdimm/pfn_devs.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/drivers/nvdimm/dax_devs.c b/drivers/nvdimm/dax_devs.c
index ba4c409ede65..aa51a9022d12 100644
--- a/drivers/nvdimm/dax_devs.c
+++ b/drivers/nvdimm/dax_devs.c
@@ -111,6 +111,10 @@ int nd_dax_probe(struct device *dev, struct nd_namespace_common *ndns)
 			return -ENOMEM;
 	}
 	pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
+	if (!pfn_sb) {
+		put_device(dax_dev);
+		return -ENOMEM;
+	}
 	nd_pfn = &nd_dax->nd_pfn;
 	nd_pfn->pfn_sb = pfn_sb;
 	rc = nd_pfn_validate(nd_pfn, DAX_SIG);
diff --git a/drivers/nvdimm/pfn_devs.c b/drivers/nvdimm/pfn_devs.c
index 42b172fc5576..6a69d8bfeb7c 100644
--- a/drivers/nvdimm/pfn_devs.c
+++ b/drivers/nvdimm/pfn_devs.c
@@ -635,6 +635,10 @@ int nd_pfn_probe(struct device *dev, struct nd_namespace_common *ndns)
 	if (!pfn_dev)
 		return -ENOMEM;
 	pfn_sb = devm_kmalloc(dev, sizeof(*pfn_sb), GFP_KERNEL);
+	if (!pfn_sb) {
+		put_device(pfn_dev);
+		return -ENOMEM;
+	}
 	nd_pfn = to_nd_pfn(pfn_dev);
 	nd_pfn->pfn_sb = pfn_sb;
 	rc = nd_pfn_validate(nd_pfn, PFN_SIG);
-- 
2.34.1