Aug 23 2009

[S390] drivers/s390: put NULL test before dereference 

Author: Julia Lawall <julia@diku.dk>

If the NULL test on block is needed, it should be before the dereference of
the base field.

The semantic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// 
@r@
expression E1,E2;
identifier fld;
statement S1,S2;
@@

E1 = E2->fld;
(
if (E1 == NULL) S1 else S2
|
*if (E2 == NULL) S1 else S2
)
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Martin Schwidefsky 

---
 drivers/s390/block/dasd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/drivers/s390/block/dasd.c b/drivers/s390/block/dasd.c
index 7498366..3f62dd5 100644
--- a/drivers/s390/block/dasd.c
+++ b/drivers/s390/block/dasd.c
@@ -2135,9 +2135,9 @@ static int dasd_getgeo(struct block_device *bdev, struct hd_geometry *geo)
 	struct dasd_device *base;
 
 	block = bdev->bd_disk->private_data;
-	base = block->base;
 	if (!block)
 		return -ENODEV;
+	base = block->base;
 
 	if (!base->discipline ||
 	    !base->discipline->fill_geometry)

qlambert