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USB: core: Avoid WARNings for 0-length descriptor requests

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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.

CC: Johan Hovold <johan@kernel.org>
Reported-and-tested-by: syzbot+7dbcd9ff34dc4ed45240@syzkaller.appspotmail.com
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Link: https://lore.kernel.org/r/20210607152307.GD1768031@rowland.harvard.edu
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Alan Stern 2021-06-07 11:23:07 -04:00 committed by Greg Kroah-Hartman
parent 307462a6f5
commit 60dfe484ce
1 changed files with 6 additions and 0 deletions
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6
drivers/usb/core/message.c
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@ -783,6 +783,9 @@ int usb_get_descriptor(struct usb_device *dev, unsigned char type,
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_device *dev, unsigned short langid,
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),