Commits
Alan Stern committed 54f83b8c8ea
USB: gadget: Reject endpoints with 0 maxpacket value Endpoints with a maxpacket length of 0 are probably useless. They can't transfer any data, and it's not at all unlikely that a UDC will crash or hang when trying to handle a non-zero-length usb_request for such an endpoint. Indeed, dummy-hcd gets a divide error when trying to calculate the remainder of a transfer length by the maxpacket value, as discovered by the syzbot fuzzer. Currently the gadget core does not check for endpoints having a maxpacket value of 0. This patch adds a check to usb_ep_enable(), preventing such endpoints from being used. As far as I know, none of the gadget drivers in the kernel tries to create an endpoint with maxpacket = 0, but until now there has been nothing to prevent userspace programs under gadgetfs or configfs from doing it. Signed-off-by: Alan Stern <stern@rowland.harvard.edu> Reported-and-tested-by: syzbot+8ab8bf161038a8768553@syzkaller.appspotmail.com CC: <stable@vger.kernel.org> Acked-by: Felipe Balbi <balbi@kernel.org> Link: https://lore.kernel.org/r/Pine.LNX.4.44L0.1910281052370.1485-100000@iolanthe.rowland.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>