There is a possible issue with the use, or lack thereof of sk_refcnt and
sk_wmem_alloc in the wifi ack status functionality.
Specifically if a socket were to request acknowledgements, and the socket
were to have sk_refcnt drop to 0 resulting in it waiting on sk_wmem_alloc
to reach 0 it would be possible to have sock_queue_err_skb orphan the last
buffer, resulting in __sk_free being called on the socket. After this the
buffer is enqueued on sk_error_queue, however the queue has already been
flushed resulting in at least a memory leak, if not a data corruption.
Signed-off-by: Alexander Duyck <alexander.h.duyck@xxxxxxxxx>
---
net/core/skbuff.c | 5 +++++
net/mac80211/tx.c | 15 ++++-----------
2 files changed, 9 insertions(+), 11 deletions(-)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index c9da77a..c8259ac 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3628,9 +3628,14 @@ void skb_complete_wifi_ack(struct sk_buff *skb, bool acked)
serr->ee.ee_errno = ENOMSG;
serr->ee.ee_origin = SO_EE_ORIGIN_TXSTATUS;
+ /* take a reference to prevent skb_orphan() from freeing the socket */
+ sock_hold(sk);
+
err = sock_queue_err_skb(sk, skb);
if (err)
kfree_skb(skb);
+
+ sock_put(sk);
}
EXPORT_SYMBOL_GPL(skb_complete_wifi_ack);
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 925c39f..cf71414 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -2072,30 +2072,23 @@ netdev_tx_t ieee80211_subif_start_xmit(struct sk_buff *skb,
if (unlikely(!multicast && skb->sk &&
skb_shinfo(skb)->tx_flags & SKBTX_WIFI_STATUS)) {
- struct sk_buff *orig_skb = skb;
+ struct sk_buff *ack_skb = skb_clone_sk(skb);
- skb = skb_clone(skb, GFP_ATOMIC);
- if (skb) {
+ if (ack_skb) {
unsigned long flags;
int id;
spin_lock_irqsave(&local->ack_status_lock, flags);
- id = idr_alloc(&local->ack_status_frames, orig_skb,
+ id = idr_alloc(&local->ack_status_frames, ack_skb,
1, 0x10000, GFP_ATOMIC);
spin_unlock_irqrestore(&local->ack_status_lock, flags);
if (id >= 0) {
info_id = id;
info_flags |= IEEE80211_TX_CTL_REQ_TX_STATUS;
- } else if (skb_shared(skb)) {
- kfree_skb(orig_skb);
} else {
- kfree_skb(skb);
- skb = orig_skb;
+ kfree_skb(ack_skb);
}
- } else {
- /* couldn't clone -- lose tx status ... */
- skb = orig_skb;
}
}
--
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