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[75.142.250.213]) by smtp.gmail.com with ESMTPSA id x185sm2883927iof.41.2020.08.30.11.36.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 30 Aug 2020 11:36:51 -0700 (PDT) From: trix@redhat.com To: balbi@kernel.org, gregkh@linuxfoundation.org, natechancellor@gmail.com, ndesaulniers@google.com, christophe.jaillet@wanadoo.fr, peter.chen@nxp.com, b-liu@ti.com, chunfeng.yun@mediatek.com, novikov@ispras.ru, yanaijie@huawei.com Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Tom Rix Subject: [PATCH] usb: gadget: net2272: assert for a valid dma request Date: Sun, 30 Aug 2020 11:36:46 -0700 Message-Id: <20200830183646.24930-1-trix@redhat.com> X-Mailer: git-send-email 2.18.1 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Tom Rix clang static analysis flags this representive problem net2272.c:1541:8: warning: Dereference of null pointer if ((req->req.length % ep->ep.maxpacket != 0) || ^~~~~~~~~~~~~~~ This is mostly not a problem. In net2272_handle_dma(), even though every path through the routine dereferences req, it is set to NULL when the ep->queue is empty. If the eq->queue was ever empty this would have oops. So the else statement should not be needed. If it is, flag it as a BUG. Signed-off-by: Tom Rix --- drivers/usb/gadget/udc/net2272.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/udc/net2272.c b/drivers/usb/gadget/udc/net2272.c index 44d1ea2307bb..8301723a8b1a 100644 --- a/drivers/usb/gadget/udc/net2272.c +++ b/drivers/usb/gadget/udc/net2272.c @@ -1506,17 +1506,16 @@ static int net2272_stop(struct usb_gadget *_gadget) static void net2272_handle_dma(struct net2272_ep *ep) { - struct net2272_request *req; + struct net2272_request *req = NULL; unsigned len; int status; if (!list_empty(&ep->queue)) req = list_entry(ep->queue.next, struct net2272_request, queue); - else - req = NULL; dev_vdbg(ep->dev->dev, "handle_dma %s req %p\n", ep->ep.name, req); + BUG_ON(!req); /* Ensure DREQ is de-asserted */ net2272_write(ep->dev, DMAREQ, -- 2.18.1