target: prevent NULL pointer dereference in target_report_luns

transport_kmap_data_sg can return NULL.  I never saw this trigger, but
returning -ENOMEM seems better than a crash.  Also removes a pointless
case while at it.

Signed-off-by: Joern Engel <joern@logfs.org>
Cc: stable@vger.kernel.org
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>

1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/target/target_core_device.c b/drivers/target/target_core_device.c
index b0572f480c04..36fa75da085c 100644
--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -652,7 +652,9 @@ int target_report_luns(struct se_task *se_task)
         unsigned char *buf;
         u32 cdb_offset = 0, lun_count = 0, offset = 8, i;
 
-        buf = (unsigned char *) transport_kmap_data_sg(se_cmd);
+        buf = transport_kmap_data_sg(se_cmd);
+        if (!buf)
+                return -ENOMEM;
 
         /*
          * If no struct se_session pointer is present, this struct se_cmd is