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wifi: zd1211rw: Fix potential NULL pointer dereference in zd_mac_tx_to_dev()

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There is a potential NULL pointer dereference in zd_mac_tx_to_dev(). For
example, the following is possible:

    	T0			    		T1
zd_mac_tx_to_dev()
  /* len == skb_queue_len(q) */
  while (len > ZD_MAC_MAX_ACK_WAITERS) {

					  filter_ack()
					    spin_lock_irqsave(&q->lock, flags);
					    /* position == skb_queue_len(q) */
					    for (i=1; i<position; i++)
				    	      skb = __skb_dequeue(q)

					    if (mac->type == NL80211_IFTYPE_AP)
					      skb = __skb_dequeue(q);
					    spin_unlock_irqrestore(&q->lock, flags);

    skb_dequeue() -> NULL

Since there is a small gap between checking skb queue length and skb being
unconditionally dequeued in zd_mac_tx_to_dev(), skb_dequeue() can return NULL.
Then the pointer is passed to zd_mac_tx_status() where it is dereferenced.

In order to avoid potential NULL pointer dereference due to situations like
above, check if skb is not NULL before passing it to zd_mac_tx_status().

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: 459c51ad6e ("zd1211rw: port to mac80211")
Signed-off-by: Daniil Dulov <d.dulov@aladdin.ru>
Link: https://patch.msgid.link/20250626114619.172631-1-d.dulov@aladdin.ru
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Daniil Dulov 2025-06-26 14:46:19 +03:00 committed by Johannes Berg
parent 1fe44a86ff
commit 74b1ec9f5d
1 changed files with 5 additions and 1 deletions
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6
drivers/net/wireless/zydas/zd1211rw/zd_mac.c
View File

@ -583,7 +583,11 @@ void zd_mac_tx_to_dev(struct sk_buff *skb, int error)
skb_queue_tail(q, skb);
while (skb_queue_len(q) > ZD_MAC_MAX_ACK_WAITERS) {
zd_mac_tx_status(hw, skb_dequeue(q),
skb = skb_dequeue(q);
if (!skb)
break;
zd_mac_tx_status(hw, skb,
mac->ack_pending ? mac->ack_signal : 0,
NULL);
mac->ack_pending = 0;