hif_dev->remain_skb is allocated and used exclusively in
ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is
processed and subsequently freed (in error paths) only during the next
call of ath9k_hif_usb_rx_stream().
So, if the urbs are deallocated between those two calls due to the device
deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream()
is not called next time and the allocated remain_skb is leaked. Our local
Syzkaller instance was able to trigger that.
remain_skb makes sense when receiving two consecutive urbs which are
logically linked together, i.e. a specific data field from the first skb
indicates a cached skb to be allocated, memcpy'd with some data and
subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs
deallocation supposedly makes that link irrelevant so we need to free the
cached skb in those cases.
Fix the leak by introducing a function to explicitly free remain_skb (if
it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL
when it has not been allocated at all (hif_dev struct is kzalloced) or
when it has been processed in next call to ath9k_hif_usb_rx_stream().
Found by Linux Verification Center (linuxtesting.org) with Syzkaller.
Fixes: fb9987d0f748 ("ath9k_htc: Support for AR9271 chipset.")
Signed-off-by: Fedor Pchelkin <pchelkin@xxxxxxxxx>
Signed-off-by: Alexey Khoroshilov <khoroshilov@xxxxxxxxx>
---
v1->v2: move ath9k_hif_usb_free_rx_remain_skb call into urbs dealloc
function as advised by Toke; add a stat macro
drivers/net/wireless/ath/ath9k/hif_usb.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index f521dfa2f194..e0130beb304d 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -534,6 +534,24 @@ static struct ath9k_htc_hif hif_usb = {
.send = hif_usb_send,
};
+/* Need to free remain_skb allocated in ath9k_hif_usb_rx_stream
+ * in case ath9k_hif_usb_rx_stream wasn't called next time to
+ * process the buffer and subsequently free it.
+ */
+static void ath9k_hif_usb_free_rx_remain_skb(struct hif_device_usb *hif_dev)
+{
+ unsigned long flags;
+
+ spin_lock_irqsave(&hif_dev->rx_lock, flags);
+ if (hif_dev->remain_skb) {
+ dev_kfree_skb_any(hif_dev->remain_skb);
+ hif_dev->remain_skb = NULL;
+ hif_dev->rx_remain_len = 0;
+ RX_STAT_INC(hif_dev, skb_dropped);
+ }
+ spin_unlock_irqrestore(&hif_dev->rx_lock, flags);
+}
+
static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
struct sk_buff *skb)
{
@@ -868,6 +886,7 @@ static int ath9k_hif_usb_alloc_tx_urbs(struct hif_device_usb *hif_dev)
static void ath9k_hif_usb_dealloc_rx_urbs(struct hif_device_usb *hif_dev)
{
usb_kill_anchored_urbs(&hif_dev->rx_submitted);
+ ath9k_hif_usb_free_rx_remain_skb(hif_dev);
}
static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
--
2.34.1
