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Wed, 20 May 2026 23:54:33 -0700 (PDT) From: Maoyi Xie To: Andrew Jeffery , Neal Liu Cc: Greg Kroah-Hartman , Benjamin Herrenschmidt , Joel Stanley , Andrew Lunn , Alan Stern , linux-aspeed@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3] usb: gadget: aspeed_udc: avoid past-the-end iterator in dequeue Date: Thu, 21 May 2026 14:54:28 +0800 Message-Id: <20260521065428.3261238-1-maoyixie.tju@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260519080213.1932516-1-maoyixie.tju@gmail.com> References: <20260519080213.1932516-1-maoyixie.tju@gmail.com> 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" 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. Default `rc` to -EINVAL and set it to 0 only inside the match branch. `req` is no longer read after the loop, so the past-the-end dereference goes away. No extra cursor variable or post-loop test is needed. Suggested-by: Alan Stern Suggested-by: Andrew Jeffery Signed-off-by: Maoyi Xie --- v3: Switch to Andrew Jeffery's shape: default rc to -EINVAL, set rc=3D0 inside the match branch, drop the post-loop check. Smaller diff, no extra cursor variable, no goto. Same semantic fix as v2. v2: https://lore.kernel.org/linux-usb/20260519080213.1932516-1-maoyixie.tju= @gmail.com/ v1: https://lore.kernel.org/linux-usb/20260518073403.1285339-1-maoyi.xie@nt= u.edu.sg/ drivers/usb/gadget/udc/aspeed_udc.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/usb/gadget/udc/aspeed_udc.c b/drivers/usb/gadget/udc/a= speed_udc.c index 7fc6696b7694..75f9c831b21a 100644 --- a/drivers/usb/gadget/udc/aspeed_udc.c +++ b/drivers/usb/gadget/udc/aspeed_udc.c @@ -694,7 +694,7 @@ static int ast_udc_ep_dequeue(struct usb_ep *_ep, struc= t usb_request *_req) struct ast_udc_dev *udc =3D ep->udc; struct ast_udc_request *req; unsigned long flags; - int rc =3D 0; + int rc =3D -EINVAL; =20 spin_lock_irqsave(&udc->lock, flags); =20 @@ -704,14 +704,11 @@ static int ast_udc_ep_dequeue(struct usb_ep *_ep, str= uct usb_request *_req) list_del_init(&req->queue); ast_udc_done(ep, req, -ESHUTDOWN); _req->status =3D -ECONNRESET; + rc =3D 0; break; } } =20 - /* dequeue request not found */ - if (&req->req !=3D _req) - rc =3D -EINVAL; - spin_unlock_irqrestore(&udc->lock, flags); =20 return rc; --=20 2.34.1