[PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Hui Peng]

The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
are initialized to point to the containing `ath6kl_usb` object
according to endpoint descriptors read from the device side, as shown
below in `ath6kl_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 = ath6kl_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 `ath6kl_usb_alloc_urb_from_pipe` and
`ath6kl_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>
---
 drivers/net/wireless/ath/ath6kl/usb.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
index 4defb7a0330f..53b66e9434c9 100644
--- a/drivers/net/wireless/ath/ath6kl/usb.c
+++ b/drivers/net/wireless/ath/ath6kl/usb.c
@@ -132,6 +132,10 @@ ath6kl_usb_alloc_urb_from_pipe(struct ath6kl_usb_pipe *pipe)
 	struct ath6kl_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 =
@@ -150,6 +154,10 @@ static void ath6kl_usb_free_urb_to_pipe(struct ath6kl_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++;
 
-- 
2.22.0

Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Greg KH]

On Sat, Aug 03, 2019 at 08:29:04PM -0400, Hui Peng wrote:
> The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
> are initialized to point to the containing `ath6kl_usb` object
> according to endpoint descriptors read from the device side, as shown
> below in `ath6kl_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 = ath6kl_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 `ath6kl_usb_alloc_urb_from_pipe` and
> `ath6kl_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>

Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Guenter Roeck]

On Sat, Aug 03, 2019 at 08:29:04PM -0400, Hui Peng wrote:
> The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
> are initialized to point to the containing `ath6kl_usb` object
> according to endpoint descriptors read from the device side, as shown
> below in `ath6kl_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 = ath6kl_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 `ath6kl_usb_alloc_urb_from_pipe` and
> `ath6kl_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>

I don't see this patch in the upstream kernel or in -next.

At the same time, it is supposed to fix CVE-2019-15098, which has
a CVSS v2.0 score of 7.8 (high).

Is this patch going to be applied to the upstream kernel ?  If not,
are there reasons to believe that the vulnerability is not as severe
as its CVSS score indicates ?

Thanks,
Guenter

> ---
>  drivers/net/wireless/ath/ath6kl/usb.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/drivers/net/wireless/ath/ath6kl/usb.c b/drivers/net/wireless/ath/ath6kl/usb.c
> index 4defb7a0330f..53b66e9434c9 100644
> --- a/drivers/net/wireless/ath/ath6kl/usb.c
> +++ b/drivers/net/wireless/ath/ath6kl/usb.c
> @@ -132,6 +132,10 @@ ath6kl_usb_alloc_urb_from_pipe(struct ath6kl_usb_pipe *pipe)
>  	struct ath6kl_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 =
> @@ -150,6 +154,10 @@ static void ath6kl_usb_free_urb_to_pipe(struct ath6kl_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++;
>  
> -- 
> 2.22.0
> 

Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Kalle Valo]

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

> On Sat, Aug 03, 2019 at 08:29:04PM -0400, Hui Peng wrote:
>> The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
>> are initialized to point to the containing `ath6kl_usb` object
>> according to endpoint descriptors read from the device side, as shown
>> below in `ath6kl_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 = ath6kl_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 `ath6kl_usb_alloc_urb_from_pipe` and
>> `ath6kl_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>
>
> I don't see this patch in the upstream kernel or in -next.
>
> At the same time, it is supposed to fix CVE-2019-15098, which has
> a CVSS v2.0 score of 7.8 (high).
>
> Is this patch going to be applied to the upstream kernel ?

Lately I have been very busy and I have not had a chance to apply ath6kl
nor ath10k patches. This patch is on my queue and my plan is to go
through my patch queue next week.

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

Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Kalle Valo]

Hui Peng <benquike@gmail.com> writes:

> The reason that this patch is still in the pending state is that it
> has not reviewed by maintainers (they are not responding).
> @Greg: can we apply it?

Who is "we" in this case? But anyway, I'll review the patch and if it's
ok I'll take it through my ath.git tree, as normal.

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

Re: [PATCH 1/2] Fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe

[Kalle Valo]

Hui Peng <benquike@gmail.com> wrote:

> The `ar_usb` field of `ath6kl_usb_pipe_usb_pipe` objects
> are initialized to point to the containing `ath6kl_usb` object
> according to endpoint descriptors read from the device side, as shown
> below in `ath6kl_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 = ath6kl_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 `ath6kl_usb_alloc_urb_from_pipe` and
> `ath6kl_usb_free_urb_to_pipe`.
> 
> This patch fixes the bug by preventing potential NULL-ptr-deref
> (CVE-2019-15098).
> 
> 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>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

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

39d170b3cb62 ath6kl: fix a NULL-ptr-deref bug in ath6kl_usb_alloc_urb_from_pipe()

-- 
https://patchwork.kernel.org/patch/11074655/

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