linux-kernel - [PATCH v2] Fix NULL pointer deref due to filtering on fork

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Message-ID: <20231011051225.3674436-1-anjali.k.kulkarni@oracle.com>
Date:   Tue, 10 Oct 2023 22:12:25 -0700
From:   Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
To:     linux-kernel@...r.kernel.org
Cc:     davem@...emloft.net, Liam.Howlett@...cle.com,
        netdev@...r.kernel.org, oliver.sang@...el.com,
        anjali.k.kulkarni@...cle.com
Subject: [PATCH v2] Fix NULL pointer deref due to filtering on fork

cn_netlink_send_mult() should be called with filter & filter_data only
for EXIT case. For all other events, filter & filter_data should be
NULL.

Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
Reported-by: kernel test robot <oliver.sang@...el.com>
Closes: https://urldefense.com/v3/__https://lore.kernel.org/oe-lkp/202309201456.84c19e27-oliver.sang@intel.com__;!!ACWV5N9M2RV99hQ!PgqlHq_nOe_KlyKkB9Mm_S8QstTJvicjuENwskatuuQK05KPuFw-KvRZeOH8iuEAMjRhkxEMPKJJnLcaT8zrPf9aqNs$

Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@...cle.com>
---
 drivers/connector/cn_proc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 05d562e9c8b1..01e17f18d187 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -104,13 +104,13 @@ static inline void send_msg(struct cn_msg *msg)
 	if (filter_data[0] == PROC_EVENT_EXIT) {
 		filter_data[1] =
 		((struct proc_event *)msg->data)->event_data.exit.exit_code;
+		cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
+				     cn_filter, (void *)filter_data);
 	} else {
-		filter_data[1] = 0;
+		cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
+				     NULL, NULL);
 	}
 
-	cn_netlink_send_mult(msg, msg->len, 0, CN_IDX_PROC, GFP_NOWAIT,
-			     cn_filter, (void *)filter_data);
-
 	local_unlock(&local_event.lock);
 }
 
-- 
2.42.0