Certain USB devices, such as the Nokia X6 mobile phone, don't expose any
endpoint descriptors on some of their interfaces. If the ACM driver is forced
to probe all interfaces on a device the a NULL pointer dereference will occur
when the ACM driver attempts to use the endpoint of the alternative settings.
One way to get the ACM driver to probe all the interfaces is by using the
/sys/bus/usb/drivers/cdc_acm/new_id interface.
This patch checks that the alternative settings and the associated endpoint
pointer are non-NULL before using them.
Signed-off-by: Toby Gray <toby.gray@xxxxxxxxxxx>
---
drivers/usb/class/cdc-acm.c | 4 +++-
1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 1833b3a..44bbeae 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -965,7 +965,9 @@ static int acm_probe(struct usb_interface *intf,
}
if (!buflen) {
- if (intf->cur_altsetting->endpoint->extralen &&
+ if (intf->cur_altsetting &&
+ intf->cur_altsetting->endpoint &&
+ intf->cur_altsetting->endpoint->extralen &&
intf->cur_altsetting->endpoint->extra) {
dev_dbg(&intf->dev,
"Seeking extra descriptors on endpoint\n");
--
1.7.0.4
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