ath9k: Fix general protection fault in ath9k_hif_usb_rx_cb

In ath9k_hif_usb_rx_cb interface number is assumed to be 0.
usb_ifnum_to_if(urb->dev, 0)
But it isn't always true.

The case reported by syzbot:
https://lore.kernel.org/linux-usb/000000000000666c9c05a1c05d12@google.com
usb 2-1: new high-speed USB device number 2 using dummy_hcd
usb 2-1: config 1 has an invalid interface number: 2 but max is 0
usb 2-1: config 1 has no interface number 0
usb 2-1: New USB device found, idVendor=0cf3, idProduct=9271, bcdDevice=
1.08
usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
general protection fault, probably for non-canonical address
0xdffffc0000000015: 0000 [#1] SMP KASAN
KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af]
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.6.0-rc5-syzkaller #0

Call Trace
__usb_hcd_giveback_urb+0x29a/0x550 drivers/usb/core/hcd.c:1650
usb_hcd_giveback_urb+0x368/0x420 drivers/usb/core/hcd.c:1716
dummy_timer+0x1258/0x32ae drivers/usb/gadget/udc/dummy_hcd.c:1966
call_timer_fn+0x195/0x6f0 kernel/time/timer.c:1404
expire_timers kernel/time/timer.c:1449 [inline]
__run_timers kernel/time/timer.c:1773 [inline]
__run_timers kernel/time/timer.c:1740 [inline]
run_timer_softirq+0x5f9/0x1500 kernel/time/timer.c:1786
__do_softirq+0x21e/0x950 kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x178/0x1a0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:546 [inline]
smp_apic_timer_interrupt+0x141/0x540 arch/x86/kernel/apic/apic.c:1146
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829

Reported-and-tested-by: syzbot+40d5d2e8a4680952f042@syzkaller.appspotmail.com
Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200404041838.10426-6-hqjagain@gmail.com

drivers/net/wireless/ath/ath9k/hif_usb.c

@@ -643,9 +643,9 @@ static void ath9k_hif_usb_rx_stream(struct hif_device_usb *hif_dev,
 
 static void ath9k_hif_usb_rx_cb(struct urb *urb)
 {
-	struct sk_buff *skb = (struct sk_buff *) urb->context;
-	struct hif_device_usb *hif_dev =
-		usb_get_intfdata(usb_ifnum_to_if(urb->dev, 0));
+	struct rx_buf *rx_buf = (struct rx_buf *)urb->context;
+	struct hif_device_usb *hif_dev = rx_buf->hif_dev;
+	struct sk_buff *skb = rx_buf->skb;
 	int ret;
 
 	if (!skb)
@@ -685,14 +685,15 @@ static void ath9k_hif_usb_rx_cb(struct urb *urb)
 	return;
 free:
 	kfree_skb(skb);
+	kfree(rx_buf);
 }
 
 static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
 {
-	struct sk_buff *skb = (struct sk_buff *) urb->context;
+	struct rx_buf *rx_buf = (struct rx_buf *)urb->context;
+	struct hif_device_usb *hif_dev = rx_buf->hif_dev;
+	struct sk_buff *skb = rx_buf->skb;
 	struct sk_buff *nskb;
-	struct hif_device_usb *hif_dev =
-		usb_get_intfdata(usb_ifnum_to_if(urb->dev, 0));
 	int ret;
 
 	if (!skb)
@@ -750,6 +751,7 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
 	return;
 free:
 	kfree_skb(skb);
+	kfree(rx_buf);
 	urb->context = NULL;
 }
 
@@ -795,7 +797,7 @@ static int ath9k_hif_usb_alloc_tx_urbs(struct hif_device_usb *hif_dev)
 	init_usb_anchor(&hif_dev->mgmt_submitted);
 
 	for (i = 0; i < MAX_TX_URB_NUM; i++) {
-		tx_buf = kzalloc(sizeof(struct tx_buf), GFP_KERNEL);
+		tx_buf = kzalloc(sizeof(*tx_buf), GFP_KERNEL);
 		if (!tx_buf)
 			goto err;
 
@@ -832,8 +834,9 @@ static void ath9k_hif_usb_dealloc_rx_urbs(struct hif_device_usb *hif_dev)
 
 static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 {
-	struct urb *urb = NULL;
+	struct rx_buf *rx_buf = NULL;
 	struct sk_buff *skb = NULL;
+	struct urb *urb = NULL;
 	int i, ret;
 
 	init_usb_anchor(&hif_dev->rx_submitted);
@@ -841,6 +844,12 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 
 	for (i = 0; i < MAX_RX_URB_NUM; i++) {
 
+		rx_buf = kzalloc(sizeof(*rx_buf), GFP_KERNEL);
+		if (!rx_buf) {
+			ret = -ENOMEM;
+			goto err_rxb;
+		}
+
 		/* Allocate URB */
 		urb = usb_alloc_urb(0, GFP_KERNEL);
 		if (urb == NULL) {
@@ -855,11 +864,14 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 			goto err_skb;
 		}
 
+		rx_buf->hif_dev = hif_dev;
+		rx_buf->skb = skb;
+
 		usb_fill_bulk_urb(urb, hif_dev->udev,
 				  usb_rcvbulkpipe(hif_dev->udev,
 						  USB_WLAN_RX_PIPE),
 				  skb->data, MAX_RX_BUF_SIZE,
-				  ath9k_hif_usb_rx_cb, skb);
+				  ath9k_hif_usb_rx_cb, rx_buf);
 
 		/* Anchor URB */
 		usb_anchor_urb(urb, &hif_dev->rx_submitted);
@@ -885,6 +897,8 @@ static int ath9k_hif_usb_alloc_rx_urbs(struct hif_device_usb *hif_dev)
 err_skb:
 	usb_free_urb(urb);
 err_urb:
+	kfree(rx_buf);
+err_rxb:
 	ath9k_hif_usb_dealloc_rx_urbs(hif_dev);
 	return ret;
 }
@@ -896,14 +910,21 @@ static void ath9k_hif_usb_dealloc_reg_in_urbs(struct hif_device_usb *hif_dev)
 
 static int ath9k_hif_usb_alloc_reg_in_urbs(struct hif_device_usb *hif_dev)
 {
-	struct urb *urb = NULL;
+	struct rx_buf *rx_buf = NULL;
 	struct sk_buff *skb = NULL;
+	struct urb *urb = NULL;
 	int i, ret;
 
 	init_usb_anchor(&hif_dev->reg_in_submitted);
 
 	for (i = 0; i < MAX_REG_IN_URB_NUM; i++) {
 
+		rx_buf = kzalloc(sizeof(*rx_buf), GFP_KERNEL);
+		if (!rx_buf) {
+			ret = -ENOMEM;
+			goto err_rxb;
+		}
+
 		/* Allocate URB */
 		urb = usb_alloc_urb(0, GFP_KERNEL);
 		if (urb == NULL) {
@@ -918,11 +939,14 @@ static int ath9k_hif_usb_alloc_reg_in_urbs(struct hif_device_usb *hif_dev)
 			goto err_skb;
 		}
 
+		rx_buf->hif_dev = hif_dev;
+		rx_buf->skb = skb;
+
 		usb_fill_int_urb(urb, hif_dev->udev,
 				  usb_rcvintpipe(hif_dev->udev,
 						  USB_REG_IN_PIPE),
 				  skb->data, MAX_REG_IN_BUF_SIZE,
-				  ath9k_hif_usb_reg_in_cb, skb, 1);
+				  ath9k_hif_usb_reg_in_cb, rx_buf, 1);
 
 		/* Anchor URB */
 		usb_anchor_urb(urb, &hif_dev->reg_in_submitted);
@@ -948,6 +972,8 @@ static int ath9k_hif_usb_alloc_reg_in_urbs(struct hif_device_usb *hif_dev)
 err_skb:
 	usb_free_urb(urb);
 err_urb:
+	kfree(rx_buf);
+err_rxb:
 	ath9k_hif_usb_dealloc_reg_in_urbs(hif_dev);
 	return ret;
 }

drivers/net/wireless/ath/ath9k/hif_usb.h

@@ -86,6 +86,11 @@ struct tx_buf {
 	struct list_head list;
 };
 
+struct rx_buf {
+	struct sk_buff *skb;
+	struct hif_device_usb *hif_dev;
+};
+
 #define HIF_USB_TX_STOP  BIT(0)
 #define HIF_USB_TX_FLUSH BIT(1)