[PATCH 51/81] isdn/gigaset: fix zero size border case in debug dump

[Herton Ronaldo Krzesinski]

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

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

From: Tilman Schmidt <tilman at imap.cc>

commit d721a1752ba544df8d7d36959038b26bc92bdf80 upstream.

If subtracting 12 from l leaves zero we'd do a zero size allocation,
leading to an oops later when we try to set the NUL terminator.

Reported-by: Dan Carpenter <dan.carpenter at oracle.com>
Signed-off-by: Tilman Schmidt <tilman at imap.cc>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
---
 drivers/isdn/gigaset/capi.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/isdn/gigaset/capi.c b/drivers/isdn/gigaset/capi.c
index 27e4a3e..f45b5b0 100644
--- a/drivers/isdn/gigaset/capi.c
+++ b/drivers/isdn/gigaset/capi.c
@@ -248,6 +248,8 @@ static inline void dump_rawmsg(enum debuglevel level, const char *tag,
 		CAPIMSG_APPID(data), CAPIMSG_MSGID(data), l,
 		CAPIMSG_CONTROL(data));
 	l -= 12;
+	if (l <= 0)
+		return;
 	dbgline = kmalloc(3 * l, GFP_ATOMIC);
 	if (!dbgline)
 		return;
-- 
1.7.9.5