| From 120357f38689baaeb32bbdc22a4b6ab882fe6df6 Mon Sep 17 00:00:00 2001 |
| From: Alan Stern <stern@rowland.harvard.edu> |
| Date: Mon, 28 Oct 2019 10:54:26 -0400 |
| Subject: [PATCH] USB: gadget: Reject endpoints with 0 maxpacket value |
| |
| commit 54f83b8c8ea9b22082a496deadf90447a326954e upstream. |
| |
| 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> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/usb/gadget/udc/core.c b/drivers/usb/gadget/udc/core.c |
| index 7cf34beb50df..4d8f8f4ecf98 100644 |
| --- a/drivers/usb/gadget/udc/core.c |
| +++ b/drivers/usb/gadget/udc/core.c |
| @@ -98,6 +98,17 @@ int usb_ep_enable(struct usb_ep *ep) |
| if (ep->enabled) |
| goto out; |
| |
| + /* UDC drivers can't handle endpoints with maxpacket size 0 */ |
| + if (usb_endpoint_maxp(ep->desc) == 0) { |
| + /* |
| + * We should log an error message here, but we can't call |
| + * dev_err() because there's no way to find the gadget |
| + * given only ep. |
| + */ |
| + ret = -EINVAL; |
| + goto out; |
| + } |
| + |
| ret = ep->ops->enable(ep, ep->desc); |
| if (ret) |
| goto out; |
| -- |
| 2.7.4 |
| |
