linux-kernel - [ 45/66] isdn/gigaset: fix zero size border case in debug dump

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Message-Id: <20130217225006.871315239@decadent.org.uk>
Date:	Sun, 17 Feb 2013 22:50:46 +0000
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	akpm@...ux-foundation.org, Tilman Schmidt <tilman@...p.cc>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	"David S. Miller" <davem@...emloft.net>
Subject: [ 45/66] isdn/gigaset: fix zero size border case in debug dump

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

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

From: Tilman Schmidt <tilman@...p.cc>

[ Upstream commit d721a1752ba544df8d7d36959038b26bc92bdf80 ]

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@...cle.com>
Signed-off-by: Tilman Schmidt <tilman@...p.cc>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 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 fd17bb3..08c2329 100644
--- a/drivers/isdn/gigaset/capi.c
+++ b/drivers/isdn/gigaset/capi.c
@@ -264,6 +264,8 @@ 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;


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