Messages in this thread | | | Date | Tue, 9 Jan 2024 17:27:49 +0530 | Subject | Re: [PATCH v3] usb: core: Prevent null pointer dereference in update_port_device_state | From | Udipto Goswami <> |
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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: stable@vger.kernel.org >> Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com> >> --- >> 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
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