[ 079/149] target: prevent NULL pointer dereference in target_report_luns

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: =?UTF-8?q?J=C3=B6rn=20Engel?= <joern@xxxxxxxxx>

commit 47f1b8803e1e358ebbf4f82bfdb98971c912a2c3 upstream.

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@xxxxxxxxx>
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/target/target_core_device.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -658,7 +658,9 @@ int target_report_luns(struct se_task *s
 	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


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