acpi, nfit: fix register dimm error handling

A NULL pointer reference kernel bug was observed when
acpi_nfit_add_dimm() called in acpi_nfit_register_dimms() failed. This
error path does not set nfit_mem->nvdimm, but the 2nd
list_for_each_entry() loop in the function assumes it's always set. Add
a check to nfit_mem->nvdimm.

Cc: <stable@vger.kernel.org>
Fixes: ba9c8dd3c222 ("acpi, nfit: add dimm device notification support")
Signed-off-by: Toshi Kani <toshi.kani@hpe.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index ff2580e7611d18c6d56c58d50c2cbc3a2d54aa36..4af0f936147ae4538b88935e89dc33c8933f548d 100644 (file)
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -1860,6 +1860,9 @@ static int acpi_nfit_register_dimms(struct acpi_nfit_desc *acpi_desc)
                struct kernfs_node *nfit_kernfs;
 
                nvdimm = nfit_mem->nvdimm;
+               if (!nvdimm)
+                       continue;
+
                nfit_kernfs = sysfs_get_dirent(nvdimm_kobj(nvdimm)->sd, "nfit");
                if (nfit_kernfs)
                        nfit_mem->flags_attr = sysfs_get_dirent(nfit_kernfs,