From: Fabian Vogt <fabian@ritter-vogt.de>
Date: Wed, 24 Mar 2021 14:11:14 +0000 (+0100)
Subject: fotg210-udc: Don't DMA more than the buffer can take
X-Git-Tag: v4.4.269~100
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=257f1877074dc58b0a927628ae57294cc109aeee;p=thirdparty%2Fkernel%2Fstable.git

fotg210-udc: Don't DMA more than the buffer can take

[ Upstream commit 3e7c2510bdfe89a9ec223dd7acd6bfc8bb1cbeb6 ]

Before this, it wrote as much as available into the buffer, even if it
didn't fit.

Fixes: b84a8dee23fd ("usb: gadget: add Faraday fotg210_udc driver")
Signed-off-by: Fabian Vogt <fabian@ritter-vogt.de>
Link: https://lore.kernel.org/r/20210324141115.9384-7-fabian@ritter-vogt.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/drivers/usb/gadget/udc/fotg210-udc.c b/drivers/usb/gadget/udc/fotg210-udc.c
index 491b04dd6db71..b2910bc65e512 100644
--- a/drivers/usb/gadget/udc/fotg210-udc.c
+++ b/drivers/usb/gadget/udc/fotg210-udc.c
@@ -340,8 +340,9 @@ static void fotg210_start_dma(struct fotg210_ep *ep,
 		} else {
 			buffer = req->req.buf + req->req.actual;
 			length = ioread32(ep->fotg210->reg +
-					FOTG210_FIBCR(ep->epnum - 1));
-			length &= FIBCR_BCFX;
+					FOTG210_FIBCR(ep->epnum - 1)) & FIBCR_BCFX;
+			if (length > req->req.length - req->req.actual)
+				length = req->req.length - req->req.actual;
 		}
 	} else {
 		buffer = req->req.buf + req->req.actual;