The USB core has utility routines to retrieve various types of
descriptors. These routines will now provoke a WARN if they are asked
to retrieve 0 bytes (USB "receive" requests must not have zero
length), so avert this by checking the size argument at the start.
Reported-and-tested-by: syzbot+7dbcd9ff34dc4ed45240@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
CC: Johan Hovold <johan@xxxxxxxxxx>
---
v2: Added extra blank lines following the sanity tests.
[as1962b]
drivers/usb/core/message.c | 6 ++++++
1 file changed, 6 insertions(+)
Index: usb-devel/drivers/usb/core/message.c
===================================================================
--- usb-devel.orig/drivers/usb/core/message.c
+++ usb-devel/drivers/usb/core/message.c
@@ -783,6 +783,9 @@ int usb_get_descriptor(struct usb_device
int i;
int result;
+ if (size <= 0) /* No point in asking for no data */
+ return -EINVAL;
+
memset(buf, 0, size); /* Make sure we parse really received data */
for (i = 0; i < 3; ++i) {
@@ -832,6 +835,9 @@ static int usb_get_string(struct usb_dev
int i;
int result;
+ if (size <= 0) /* No point in asking for no data */
+ return -EINVAL;
+
for (i = 0; i < 3; ++i) {
/* retry on length 0 or stall; some devices are flakey */
result = usb_control_msg(dev, usb_rcvctrlpipe(dev, 0),
