[PATCH] driver/ata: fix potential null pointer dereference on pointer last_sge

[Chengfeng Ye]

The pointer cs_desc could be null if the loop is not
executed, so there is a potential NULL-PTR dereference
issue. Fix this by adding a null check before dereference.

Signed-off-by: Chengfeng Ye <cyeaa@xxxxxxxxxxxxxx>
---
 drivers/ata/sata_sil24.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/ata/sata_sil24.c b/drivers/ata/sata_sil24.c
index 06a1e27c4f84..2bd595da799f 100644
--- a/drivers/ata/sata_sil24.c
+++ b/drivers/ata/sata_sil24.c
@@ -785,6 +785,8 @@ static inline void sil24_fill_sg(struct ata_queued_cmd *qc,
 		sge++;
 	}
 
+	if (!last_sge)
+		return;
 	last_sge->flags = cpu_to_le32(SGE_TRM);
 }
 
-- 
2.17.1