[PATCH] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[PATCH] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[Fedor Pchelkin]

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>
---
 drivers/net/wireless/ath/ath9k/hif_usb.c | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
index 518deb5098a2..b70128d1594d 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -708,14 +708,13 @@ 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:
@@ -724,7 +723,7 @@ 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);
@@ -740,20 +739,19 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
 				 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);
 	}
 
@@ -762,12 +760,13 @@ 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;
 }
-- 
2.25.1

Re: [PATCH] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[Toke Høiland-Jørgensen]

Fedor Pchelkin <pchelkin@ispras.ru> writes:

> 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>
> ---
>  drivers/net/wireless/ath/ath9k/hif_usb.c | 21 ++++++++++-----------
>  1 file changed, 10 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/net/wireless/ath/ath9k/hif_usb.c b/drivers/net/wireless/ath/ath9k/hif_usb.c
> index 518deb5098a2..b70128d1594d 100644
> --- a/drivers/net/wireless/ath/ath9k/hif_usb.c
> +++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
> @@ -708,14 +708,13 @@ 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:
> @@ -724,7 +723,7 @@ 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);
> @@ -740,20 +739,19 @@ static void ath9k_hif_usb_reg_in_cb(struct urb *urb)
>  				 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) {

The fix LGTM, but could you please add a comment here stating that the
ath9k_htc_rx_msg() call above frees the skb (either here, or as part of
the comment above the call to that function)? Also, please get rid of
the double blank line while you're fixing things up...

-Toke

[PATCH v2] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[Fedor Pchelkin]

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>
---
v1->v2: add comment about freeing an skb and remove double blank line

 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 4d9002a9d082..401b408cb7a4 100644
--- a/drivers/net/wireless/ath/ath9k/hif_usb.c
+++ b/drivers/net/wireless/ath/ath9k/hif_usb.c
@@ -708,14 +708,13 @@ 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:
@@ -724,7 +723,7 @@ 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);
@@ -735,25 +734,27 @@ 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);
 	}
 
@@ -762,12 +763,13 @@ 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;
 }
-- 
2.25.1

Re: [PATCH v2] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[Toke Høiland-Jørgensen]

Fedor Pchelkin <pchelkin@ispras.ru> writes:

> 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>

Re: [PATCH v2] ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

[Kalle Valo]

Fedor Pchelkin <pchelkin@ispras.ru> wrote:

> 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>

Patch applied to ath-next branch of ath.git, thanks.

dd95f2239fc8 wifi: ath9k: hif_usb: Fix use-after-free in ath9k_hif_usb_reg_in_cb()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20221008114917.21404-1-pchelkin@ispras.ru/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches