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Mon, 18 May 2026 00:34:09 -0700 (PDT) Received: from csl-conti-dell7858.ntu.edu.sg ([155.69.195.57]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-83f19775ca3sm14500746b3a.14.2026.05.18.00.34.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 18 May 2026 00:34:08 -0700 (PDT) From: Maoyi Xie X-Google-Original-From: Maoyi Xie To: Andrew Jeffery , Neal Liu Cc: Greg Kroah-Hartman , Benjamin Herrenschmidt , Joel Stanley , Andrew Jeffery , linux-aspeed@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] usb: gadget: aspeed_udc: avoid past-the-end iterator in dequeue Date: Mon, 18 May 2026 15:34:03 +0800 Message-Id: <20260518073403.1285339-1-maoyi.xie@ntu.edu.sg> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Maoyi Xie ast_udc_ep_dequeue() declares the loop cursor `req` outside the list_for_each_entry(). After the loop it tests `&req->req !=3D _req` to decide whether the request was found. If the queue holds no match, `req` is past-the-end. It then aliases container_of(&ep->queue, struct ast_udc_request, queue) via offset cancellation. Whether that synthetic address equals `_req` depends on heap layout. The function can return 0 without dequeueing anything. Use the cursor-vs-result idiom from the sibling aspeed-vhub driver, ast_vhub_epn_dequeue() in drivers/usb/gadget/udc/aspeed-vhub/epn.c. A separate `iter` walks the list. `req` is set only when a request matches. After the loop, `req` is NULL if nothing matched. The same idiom is used by the other UDC drivers in drivers/usb/gadget/udc/ (at91_udc, atmel_usba_udc, dummy_hcd, fsl_qe_udc, fsl_udc_core, goku_udc, gr_udc, lpc32xx_udc, max3420_udc, net2280, omap_udc, pxa25x_udc, pxa27x_udc, udc-xilinx, bcm63xx_udc). Signed-off-by: Maoyi Xie --- drivers/usb/gadget/udc/aspeed_udc.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) --- a/drivers/usb/gadget/udc/aspeed_udc.c +++ b/drivers/usb/gadget/udc/aspeed_udc.c @@ -692,26 +692,30 @@ { struct ast_udc_ep *ep =3D to_ast_ep(_ep); struct ast_udc_dev *udc =3D ep->udc; - struct ast_udc_request *req; + struct ast_udc_request *req =3D NULL, *iter; unsigned long flags; int rc =3D 0; =20 spin_lock_irqsave(&udc->lock, flags); =20 /* make sure it's actually queued on this endpoint */ - list_for_each_entry(req, &ep->queue, queue) { - if (&req->req =3D=3D _req) { - list_del_init(&req->queue); - ast_udc_done(ep, req, -ESHUTDOWN); - _req->status =3D -ECONNRESET; - break; - } + list_for_each_entry(iter, &ep->queue, queue) { + if (&iter->req !=3D _req) + continue; + req =3D iter; + break; } =20 - /* dequeue request not found */ - if (&req->req !=3D _req) + if (!req) { rc =3D -EINVAL; + goto out; + } + + list_del_init(&req->queue); + ast_udc_done(ep, req, -ESHUTDOWN); + _req->status =3D -ECONNRESET; =20 +out: spin_unlock_irqrestore(&udc->lock, flags); =20 return rc; --=20 2.34.1