Apr 02 2010

mtd: maps: Eliminate use after free 

Author: Julia Lawall <julia@diku.dk>

Moved the debugging message before the call to map_destroy, which frees its
argument.  The message is also slightly changed to reflect its new
position.

A simplified version of the semantic patch that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// 
@@
expression E,E2;
@@

del_mtd_device(E)
...
(
  E = E2
|
* E
)
// 

Signed-off-by: Julia Lawall 
Signed-off-by: Artem Bityutskiy 
Signed-off-by: David Woodhouse 

---
 drivers/mtd/maps/pcmciamtd.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
 
diff --git a/drivers/mtd/maps/pcmciamtd.c b/drivers/mtd/maps/pcmciamtd.c
index 689d6a7..81159d7 100644
--- a/drivers/mtd/maps/pcmciamtd.c
+++ b/drivers/mtd/maps/pcmciamtd.c
@@ -692,8 +692,8 @@ static void pcmciamtd_detach(struct pcmcia_device *link)
 
 	if(dev->mtd_info) {
 		del_mtd_device(dev->mtd_info);
+		info("mtd%d: Removing", dev->mtd_info->index);
 		map_destroy(dev->mtd_info);
-		info("mtd%d: Removed", dev->mtd_info->index);
 	}
 
 	pcmciamtd_release(link);

qlambert