netdev - [PATCH v2] s390/netiucv: handle memory allocation failure in conn_action

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Date: Tue, 25 Jun 2024 11:48:20 +0900
From: yskelg@...il.com
To: Alexandra Winter <wintera@...ux.ibm.com>,
	Thorsten Winkler <twinkler@...ux.ibm.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	Markus Elfring <Markus.Elfring@....de>
Cc: MichelleJin <shjy180909@...il.com>,
	linux-s390@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Yunseong Kim <yskelg@...il.com>
Subject: [PATCH v2] s390/netiucv: handle memory allocation failure in conn_action_start()

From: Yunseong Kim <yskelg@...il.com>

A null pointer is stored in the data structure member "path" after a call
of the function "iucv_path_alloc" failed. This pointer was passed to
a subsequent call of the function "iucv_path_connect" where an undesirable
dereference will be performed then. Thus add a corresponding return value
check. This prevent null pointer dereferenced kernel panic when memory
exhausted situation with the netiucv driver operating as an FSM state
in "conn_action_start".

Fixes: eebce3856737 ("[S390]: Adapt netiucv driver to new IUCV API")
Cc: linux-s390@...r.kernel.org
Signed-off-by: Yunseong Kim <yskelg@...il.com>
---
 drivers/s390/net/netiucv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/s390/net/netiucv.c b/drivers/s390/net/netiucv.c
index 039e18d46f76..d3ae78c0240f 100644
--- a/drivers/s390/net/netiucv.c
+++ b/drivers/s390/net/netiucv.c
@@ -855,6 +855,9 @@ static void conn_action_start(fsm_instance *fi, int event, void *arg)
 
 	fsm_newstate(fi, CONN_STATE_SETUPWAIT);
 	conn->path = iucv_path_alloc(NETIUCV_QUEUELEN_DEFAULT, 0, GFP_KERNEL);
+	if (!conn->path)
+		return;
+
 	IUCV_DBF_TEXT_(setup, 2, "%s: connecting to %s ...\n",
 		netdev->name, netiucv_printuser(conn));
 
-- 
2.45.2