[PATCH 5.15 142/731] wifi: ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

Greg Kroah-Hartman
2022-12-28T14:53:28Z

From: Fedor Pchelkin <pchelkin@ispras.ru>

[ Upstream commit dd95f2239fc846795fc926787c3ae0ca701c9840 ]

It is possible that skb is freed in ath9k_htc_rx_msg(), then
usb_submit_urb() fails and we try to free skb again. It causes
use-after-free bug. Moreover, if alloc_skb() fails, urb->context becomes
NULL but rx_buf is not freed and there can be a memory leak.

The patch removes unnecessary nskb and makes skb processing more clear: it
is supposed that ath9k_htc_rx_msg() either frees old skb or passes its
managing to another callback function.

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

Fixes: 3deff76095c4 ("ath9k_htc: Increase URB count for REG_IN pipe")
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/20221008114917.21404-1-pchelkin@ispras.ru
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/wireless/ath/ath9k/hif_usb.c | 28 +++++++++++++-----------
1 file changed, 15 insertions(+), 13 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index e66518d86882..e5d5b0761881 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -709,14 +709,13 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
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;
int ret;

if (!skb)
return;

if (!hif_dev)
- goto free;
+ goto free_skb;

switch (urb->status) {
case 0:
@@ -725,7 +724,7 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
case -ECONNRESET:
case -ENODEV:
case -ESHUTDOWN:
- goto free;
+ goto free_skb;
default:
skb_reset_tail_pointer(skb);
skb_trim(skb, 0);
@@ -736,25 +735,27 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
if (likely(urb->actual_length != 0)) {
skb_put(skb, urb->actual_length);

- /* Process the command first */
+ /*
+ * Process the command first.
+ * skb is either freed here or passed to be
+ * managed to another callback function.
+ */
ath9k_htc_rx_msg(hif_dev->htc_handle, skb,
skb->len, USB_REG_IN_PIPE);

-
- nskb = alloc_skb(MAX_REG_IN_BUF_SIZE, GFP_ATOMIC);
- if (!nskb) {
+ skb = alloc_skb(MAX_REG_IN_BUF_SIZE, GFP_ATOMIC);
+ if (!skb) {
dev_err(&hif_dev->udev->dev,
"ath9k_htc: REG_IN memory allocation failure\n");
- urb->context = NULL;
- return;
+ goto free_rx_buf;
}

- rx_buf->skb = nskb;
+ rx_buf->skb = skb;

usb_fill_int_urb(urb, hif_dev->udev,
usb_rcvintpipe(hif_dev->udev,
USB_REG_IN_PIPE),
- nskb->data, MAX_REG_IN_BUF_SIZE,
+ skb->data, MAX_REG_IN_BUF_SIZE,
ath9k_hif_usb_reg_in_cb, rx_buf, 1);
}

@@ -763,12 +764,13 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
ret = usb_submit_urb(urb, GFP_ATOMIC);
if (ret) {
usb_unanchor_urb(urb);
- goto free;
+ goto free_skb;
}

return;
-free:
+free_skb:
kfree_skb(skb);
+free_rx_buf:
kfree(rx_buf);
urb->context = NULL;
}
--
2.35.1