net: rose: fix invalid array index in rose_kill_by_device()

rose_kill_by_device() collects sockets into a local array[] and then
iterates over them to disconnect sockets bound to a device being brought
down.

The loop mistakenly indexes array[cnt] instead of array[i]. For cnt <
ARRAY_SIZE(array), this reads an uninitialized entry; for cnt ==
ARRAY_SIZE(array), it is an out-of-bounds read. Either case can lead to
an invalid socket pointer dereference and also leaks references taken
via sock_hold().

Fix the index to use i.

Fixes: 64b8bc7 ("net/rose: fix races in rose_kill_by_device()")
Co-developed-by: Fatma Alwasmi <[email protected]>
Signed-off-by: Fatma Alwasmi <[email protected]>
Signed-off-by: Pwnverse <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: PwnVerse

net/rose/af_rose.c

@@ -205,7 +205,7 @@ static void rose_kill_by_device(struct net_device *dev)
 	spin_unlock_bh(&rose_list_lock);
 
 	for (i = 0; i < cnt; i++) {
-		sk = array[cnt];
+		sk = array[i];
 		rose = rose_sk(sk);
 		lock_sock(sk);
 		spin_lock_bh(&rose_list_lock);