Currently,the function update_port_device_state gets the usb_hub from
udev->parent by calling usb_hub_to_struct_hub.
However, in case the actconfig or the maxchild is 0, the usb_hub would
be NULL and upon further accessing to get port_dev would result in null
pointer dereference.
Fix this by introducing an if check after the usb_hub is populated.
Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
Cc: [email protected]
Signed-off-by: Udipto Goswami <[email protected]>
---
v3: Re-wrote the comment for better context.
v2: Introduced comment for the if check & CC'ed stable.
drivers/usb/core/hub.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index ffd7c99e24a3..6b514546e59b 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev)
if (udev->parent) {
hub = usb_hub_to_struct_hub(udev->parent);
- port_dev = hub->ports[udev->portnum - 1];
- WRITE_ONCE(port_dev->state, udev->state);
- sysfs_notify_dirent(port_dev->state_kn);
+
+ /*
+ * The Link Layer Validation System Driver (lvstest)
+ * has procedure of unbinding the hub before running
+ * the rest of the procedure. This triggers
+ * hub_disconnect will set the hub's maxchild to 0.
+ * This would result usb_hub_to_struct_hub in this
+ * function to return NULL.
+ *
+ * Add if check to avoid running into NULL pointer
+ * de-reference.
+ */
+ if (hub) {
+ port_dev = hub->ports[udev->portnum - 1];
+ WRITE_ONCE(port_dev->state, udev->state);
+ sysfs_notify_dirent(port_dev->state_kn);
+ }
}
}
--
2.17.1
On 1/9/24 9:17 AM, Udipto Goswami wrote:
> Currently,the function update_port_device_state gets the usb_hub from
> udev->parent by calling usb_hub_to_struct_hub.
> However, in case the actconfig or the maxchild is 0, the usb_hub would
> be NULL and upon further accessing to get port_dev would result in null
> pointer dereference.
>
> Fix this by introducing an if check after the usb_hub is populated.
>
> Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
> Cc: [email protected]
> Signed-off-by: Udipto Goswami <[email protected]>
> ---
> v3: Re-wrote the comment for better context.
> v2: Introduced comment for the if check & CC'ed stable.
>
> drivers/usb/core/hub.c | 20 +++++++++++++++++---
> 1 file changed, 17 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
> index ffd7c99e24a3..6b514546e59b 100644
> --- a/drivers/usb/core/hub.c
> +++ b/drivers/usb/core/hub.c
> @@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev)
>
> if (udev->parent) {
> hub = usb_hub_to_struct_hub(udev->parent);
> - port_dev = hub->ports[udev->portnum - 1];
> - WRITE_ONCE(port_dev->state, udev->state);
> - sysfs_notify_dirent(port_dev->state_kn);
> +
> + /*
> + * The Link Layer Validation System Driver (lvstest)
> + * has procedure of unbinding the hub before running
> + * the rest of the procedure. This triggers
> + * hub_disconnect will set the hub's maxchild to 0.
I can't parse this sentence, s/th is missing...
> + * This would result usb_hub_to_struct_hub in this
> + * function to return NULL.
"This would result in usb_hub_to_struct_hub in this function
returning NULL", perhaps?
> + *
> + * Add if check to avoid running into NULL pointer
> + * de-reference.
> + */
> + if (hub) {
> + port_dev = hub->ports[udev->portnum - 1];
> + WRITE_ONCE(port_dev->state, udev->state);
> + sysfs_notify_dirent(port_dev->state_kn);
> + }
> }
> }
>
MBR, Sergey
Hi Sergei,
On 1/9/2024 3:01 PM, Sergei Shtylyov wrote:
> On 1/9/24 9:17 AM, Udipto Goswami wrote:
>
>> Currently,the function update_port_device_state gets the usb_hub from
>> udev->parent by calling usb_hub_to_struct_hub.
>> However, in case the actconfig or the maxchild is 0, the usb_hub would
>> be NULL and upon further accessing to get port_dev would result in null
>> pointer dereference.
>>
>> Fix this by introducing an if check after the usb_hub is populated.
>>
>> Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
>> Cc: [email protected]
>> Signed-off-by: Udipto Goswami <[email protected]>
>> ---
>> v3: Re-wrote the comment for better context.
>> v2: Introduced comment for the if check & CC'ed stable.
>>
>> drivers/usb/core/hub.c | 20 +++++++++++++++++---
>> 1 file changed, 17 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>> index ffd7c99e24a3..6b514546e59b 100644
>> --- a/drivers/usb/core/hub.c
>> +++ b/drivers/usb/core/hub.c
>> @@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev)
>>
>> if (udev->parent) {
>> hub = usb_hub_to_struct_hub(udev->parent);
>> - port_dev = hub->ports[udev->portnum - 1];
>> - WRITE_ONCE(port_dev->state, udev->state);
>> - sysfs_notify_dirent(port_dev->state_kn);
>> +
>> + /*
>> + * The Link Layer Validation System Driver (lvstest)
>> + * has procedure of unbinding the hub before running
>> + * the rest of the procedure. This triggers
>> + * hub_disconnect will set the hub's maxchild to 0.
>
> I can't parse this sentence, s/th is missing...
Thanks for the review.
Maybe this would sound better?
"This triggers hub_disconnect which will set hub's maxchild to 0"
>
>> + * This would result usb_hub_to_struct_hub in this
>> + * function to return NULL.
>
> "This would result in usb_hub_to_struct_hub in this function
> returning NULL", perhaps?
yah sound better. Will take care of it in next version.
Thanks,
-Udipto
On 1/9/24 2:57 PM, Udipto Goswami wrote:
[...]
>>> Currently,the function update_port_device_state gets the usb_hub from
>>> udev->parent by calling usb_hub_to_struct_hub.
>>> However, in case the actconfig or the maxchild is 0, the usb_hub would
>>> be NULL and upon further accessing to get port_dev would result in null
>>> pointer dereference.
>>>
>>> Fix this by introducing an if check after the usb_hub is populated.
>>>
>>> Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
>>> Cc: [email protected]
>>> Signed-off-by: Udipto Goswami <[email protected]>
>>> ---
>>> v3: Re-wrote the comment for better context.
>>> v2: Introduced comment for the if check & CC'ed stable.
>>>
>>> drivers/usb/core/hub.c | 20 +++++++++++++++++---
>>> 1 file changed, 17 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>>> index ffd7c99e24a3..6b514546e59b 100644
>>> --- a/drivers/usb/core/hub.c
>>> +++ b/drivers/usb/core/hub.c
>>> @@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev)
>>> if (udev->parent) {
>>> hub = usb_hub_to_struct_hub(udev->parent);
>>> - port_dev = hub->ports[udev->portnum - 1];
>>> - WRITE_ONCE(port_dev->state, udev->state);
>>> - sysfs_notify_dirent(port_dev->state_kn);
>>> +
>>> + /*
>>> + * The Link Layer Validation System Driver (lvstest)
>>> + * has procedure of unbinding the hub before running
>>> + * the rest of the procedure. This triggers
>>> + * hub_disconnect will set the hub's maxchild to 0.
>>
>> I can't parse this sentence, s/th is missing...
> Thanks for the review.
> Maybe this would sound better?
>
> "This triggers hub_disconnect which will set hub's maxchild to 0"
That seems parsable. :-)
>>> + * This would result usb_hub_to_struct_hub in this
>>> + * function to return NULL.
>>
>> "This would result in usb_hub_to_struct_hub in this function
>> returning NULL", perhaps?
>
> yah sound better. Will take care of it in next version.
Probably "in this function" should be dropped altogether...
> Thanks,
> -Udipto
MBR, Sergey
On 1/9/2024 8:10 PM, Sergei Shtylyov wrote:
> On 1/9/24 2:57 PM, Udipto Goswami wrote:
> [...]
>
>>>> Currently,the function update_port_device_state gets the usb_hub from
>>>> udev->parent by calling usb_hub_to_struct_hub.
>>>> However, in case the actconfig or the maxchild is 0, the usb_hub would
>>>> be NULL and upon further accessing to get port_dev would result in null
>>>> pointer dereference.
>>>>
>>>> Fix this by introducing an if check after the usb_hub is populated.
>>>>
>>>> Fixes: 83cb2604f641 ("usb: core: add sysfs entry for usb device state")
>>>> Cc: [email protected]
>>>> Signed-off-by: Udipto Goswami <[email protected]>
>>>> ---
>>>> v3: Re-wrote the comment for better context.
>>>> v2: Introduced comment for the if check & CC'ed stable.
>>>>
>>>> drivers/usb/core/hub.c | 20 +++++++++++++++++---
>>>> 1 file changed, 17 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
>>>> index ffd7c99e24a3..6b514546e59b 100644
>>>> --- a/drivers/usb/core/hub.c
>>>> +++ b/drivers/usb/core/hub.c
>>>> @@ -2053,9 +2053,23 @@ static void update_port_device_state(struct usb_device *udev)
>>>> if (udev->parent) {
>>>> hub = usb_hub_to_struct_hub(udev->parent);
>>>> - port_dev = hub->ports[udev->portnum - 1];
>>>> - WRITE_ONCE(port_dev->state, udev->state);
>>>> - sysfs_notify_dirent(port_dev->state_kn);
>>>> +
>>>> + /*
>>>> + * The Link Layer Validation System Driver (lvstest)
>>>> + * has procedure of unbinding the hub before running
>>>> + * the rest of the procedure. This triggers
>>>> + * hub_disconnect will set the hub's maxchild to 0.
>>>
>>> I can't parse this sentence, s/th is missing...
>> Thanks for the review.
>> Maybe this would sound better?
>>
>> "This triggers hub_disconnect which will set hub's maxchild to 0"
>
> That seems parsable. :-)
>
>>>> + * This would result usb_hub_to_struct_hub in this
>>>> + * function to return NULL.
>>>
>>> "This would result in usb_hub_to_struct_hub in this function
>>> returning NULL", perhaps?
>>
>> yah sound better. Will take care of it in next version.
>
> Probably "in this function" should be dropped altogether...
sure, i'll remove in v4.
Thanks,
-Udipto