[PATCH v2] Fix NULL pointer dereference in cn_filter()

[Anjali Kulkarni]

Check that sk_user_data is not NULL, else return from cn_filter().
Could not reproduce this issue, but Oliver Sang verified it has fixed
the "Closes" problem below.

Fixes: 2aa1f7a1f47c ("connector/cn_proc: Add filtering to fix some bugs")
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202309201456.84c19e27-oliver.sang@xxxxxxxxx/
Signed-off-by: Anjali Kulkarni <anjali.k.kulkarni@xxxxxxxxxx>
---
 drivers/connector/cn_proc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/connector/cn_proc.c b/drivers/connector/cn_proc.c
index 05d562e9c8b1..44b19e696176 100644
--- a/drivers/connector/cn_proc.c
+++ b/drivers/connector/cn_proc.c
@@ -54,7 +54,7 @@ static int cn_filter(struct sock *dsk, struct sk_buff *skb, void *data)
 	enum proc_cn_mcast_op mc_op;
 	uintptr_t val;
 
-	if (!dsk || !data)
+	if (!dsk || !dsk->sk_user_data || !data)
 		return 0;
 
 	ptr = (__u32 *)data;
-- 
2.42.0