[PATCH v2] ath10k: Fix a NULL-ptr-deref bug in ath10k_usb_alloc_urb_from_pipe

[PATCH v2] ath10k: Fix a NULL-ptr-deref bug in ath10k_usb_alloc_urb_from_pipe

[Guenter Roeck]

From: Hui Peng <benquike@gmail.com>

The `ar_usb` field of `ath10k_usb_pipe_usb_pipe` objects
are initialized to point to the containing `ath10k_usb` object
according to endpoint descriptors read from the device side, as shown
below in `ath10k_usb_setup_pipe_resources`:

for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
        endpoint = &iface_desc->endpoint[i].desc;

        // get the address from endpoint descriptor
        pipe_num = ath10k_usb_get_logical_pipe_num(ar_usb,
                                                endpoint->bEndpointAddress,
                                                &urbcount);
        ......
        // select the pipe object
        pipe = &ar_usb->pipes[pipe_num];

        // initialize the ar_usb field
        pipe->ar_usb = ar_usb;
}

The driver assumes that the addresses reported in endpoint
descriptors from device side  to be complete. If a device is
malicious and does not report complete addresses, it may trigger
NULL-ptr-deref `ath10k_usb_alloc_urb_from_pipe` and
`ath10k_usb_free_urb_to_pipe`.

This patch fixes the bug by preventing potential NULL-ptr-deref.

Signed-off-by: Hui Peng <benquike@gmail.com>
Reported-by: Hui Peng <benquike@gmail.com>
Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[groeck: Add driver tag to subject, fix build warning]
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: Fix build warning, add "ath10k:" to subject

 drivers/net/wireless/ath/ath10k/usb.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/usb.c b/drivers/net/wireless/ath/ath10k/usb.c
index e1420f67f776..9ebe74ee4aef 100644
--- a/drivers/net/wireless/ath/ath10k/usb.c
+++ b/drivers/net/wireless/ath/ath10k/usb.c
@@ -38,6 +38,10 @@ ath10k_usb_alloc_urb_from_pipe(struct ath10k_usb_pipe *pipe)
 	struct ath10k_urb_context *urb_context = NULL;
 	unsigned long flags;
 
+	/* bail if this pipe is not initialized */
+	if (!pipe->ar_usb)
+		return NULL;
+
 	spin_lock_irqsave(&pipe->ar_usb->cs_lock, flags);
 	if (!list_empty(&pipe->urb_list_head)) {
 		urb_context = list_first_entry(&pipe->urb_list_head,
@@ -55,6 +59,10 @@ static void ath10k_usb_free_urb_to_pipe(struct ath10k_usb_pipe *pipe,
 {
 	unsigned long flags;
 
+	/* bail if this pipe is not initialized */
+	if (!pipe->ar_usb)
+		return;
+
 	spin_lock_irqsave(&pipe->ar_usb->cs_lock, flags);
 
 	pipe->urb_cnt++;
-- 
2.17.1

Re: [PATCH v2] ath10k: Fix a NULL-ptr-deref bug in ath10k_usb_alloc_urb_from_pipe

[Kalle Valo]

Guenter Roeck <linux@roeck-us.net> wrote:

> The `ar_usb` field of `ath10k_usb_pipe_usb_pipe` objects
> are initialized to point to the containing `ath10k_usb` object
> according to endpoint descriptors read from the device side, as shown
> below in `ath10k_usb_setup_pipe_resources`:
> 
> for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
>         endpoint = &iface_desc->endpoint[i].desc;
> 
>         // get the address from endpoint descriptor
>         pipe_num = ath10k_usb_get_logical_pipe_num(ar_usb,
>                                                 endpoint->bEndpointAddress,
>                                                 &urbcount);
>         ......
>         // select the pipe object
>         pipe = &ar_usb->pipes[pipe_num];
> 
>         // initialize the ar_usb field
>         pipe->ar_usb = ar_usb;
> }
> 
> The driver assumes that the addresses reported in endpoint
> descriptors from device side  to be complete. If a device is
> malicious and does not report complete addresses, it may trigger
> NULL-ptr-deref `ath10k_usb_alloc_urb_from_pipe` and
> `ath10k_usb_free_urb_to_pipe`.
> 
> This patch fixes the bug by preventing potential NULL-ptr-deref.
> 
> Signed-off-by: Hui Peng <benquike@gmail.com>
> Reported-by: Hui Peng <benquike@gmail.com>
> Reported-by: Mathias Payer <mathias.payer@nebelwelt.net>
> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> [groeck: Add driver tag to subject, fix build warning]
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

bfd6e6e6c5d2 ath10k: Fix a NULL-ptr-deref bug in ath10k_usb_alloc_urb_from_pipe

-- 
https://patchwork.kernel.org/patch/11198433/

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