netdev - [PATCH] packet: Improve exception handling in fanout

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Date: Sun, 31 Dec 2023 16:39:02 +0100
From: Markus Elfring <Markus.Elfring@....de>
To: netdev@...r.kernel.org, kernel-janitors@...r.kernel.org,
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
 Willem de Bruijn <willemdebruijn.kernel@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] packet: Improve exception handling in fanout_add()

From: Markus Elfring <elfring@...rs.sourceforge.net>
Date: Sun, 31 Dec 2023 16:30:51 +0100

The kfree() function was called in some cases by the fanout_add() function
even if the passed variable contained a null pointer.
This issue was detected by using the Coccinelle software.

Thus use another label.

Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
---
 net/packet/af_packet.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 5f1757a32842..0681d4f1ed85 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1712,14 +1712,14 @@ static int fanout_add(struct sock *sk, struct fanout_args *args)

 	err = -EALREADY;
 	if (po->fanout)
-		goto out;
+		goto unlock_mutex;

 	if (type == PACKET_FANOUT_ROLLOVER ||
 	    (type_flags & PACKET_FANOUT_FLAG_ROLLOVER)) {
 		err = -ENOMEM;
 		rollover = kzalloc(sizeof(*rollover), GFP_KERNEL);
 		if (!rollover)
-			goto out;
+			goto unlock_mutex;
 		atomic_long_set(&rollover->num, 0);
 		atomic_long_set(&rollover->num_huge, 0);
 		atomic_long_set(&rollover->num_failed, 0);
@@ -1812,6 +1812,7 @@ static int fanout_add(struct sock *sk, struct fanout_args *args)

 out:
 	kfree(rollover);
+unlock_mutex:
 	mutex_unlock(&fanout_mutex);
 	return err;
 }
--
2.43.0