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Fri, 10 Apr 2026 03:12:32 -0700 (PDT) Received: from localhost ([196.207.164.177]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-43d63de2a48sm6924209f8f.7.2026.04.10.03.12.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 10 Apr 2026 03:12:32 -0700 (PDT) Date: Fri, 10 Apr 2026 13:12:29 +0300 From: Dan Carpenter To: Oliver Neukum Cc: linux-media@vger.kernel.org Subject: [bug report] media: rc: ttusbir: respect DMA coherency rules Message-ID: Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hello Oliver Neukum, Commit 50acaad3d202 ("media: rc: ttusbir: respect DMA coherency rules") from Feb 11, 2026 (linux-next), leads to the following Smatch static checker warning: drivers/media/rc/ttusbir.c:281 ttusbir_probe() error: we previously assumed 'tt->bulk_buffer' could be null (see line 198) drivers/media/rc/ttusbir.c 180 static int ttusbir_probe(struct usb_interface *intf, 181 const struct usb_device_id *id) 182 { 183 struct ttusbir *tt; 184 struct usb_interface_descriptor *idesc; 185 struct usb_endpoint_descriptor *desc; 186 struct rc_dev *rc; 187 int i, j, ret; 188 int altsetting = -1; 189 u8 *buffer; 190 191 tt = kzalloc_obj(*tt); 192 buffer = kzalloc(5, GFP_KERNEL); 193 rc = rc_allocate_device(RC_DRIVER_IR_RAW); 194 if (!tt || !rc || buffer) { This ! in !buffer is missing. 195 ret = -ENOMEM; 196 goto out; 197 } 198 tt->bulk_buffer = buffer; 199 200 /* find the correct alt setting */ 201 for (i = 0; i < intf->num_altsetting && altsetting == -1; i++) { 202 int max_packet, bulk_out_endp = -1, iso_in_endp = -1; 203 204 idesc = &intf->altsetting[i].desc; 205 206 for (j = 0; j < idesc->bNumEndpoints; j++) { 207 desc = &intf->altsetting[i].endpoint[j].desc; 208 max_packet = le16_to_cpu(desc->wMaxPacketSize); 209 if (usb_endpoint_dir_in(desc) && 210 usb_endpoint_xfer_isoc(desc) && 211 max_packet == 0x10) 212 iso_in_endp = j; 213 else if (usb_endpoint_dir_out(desc) && 214 usb_endpoint_xfer_bulk(desc) && 215 max_packet == 0x20) 216 bulk_out_endp = j; 217 218 if (bulk_out_endp != -1 && iso_in_endp != -1) { 219 tt->bulk_out_endp = bulk_out_endp; 220 tt->iso_in_endp = iso_in_endp; 221 altsetting = i; 222 break; 223 } 224 } 225 } 226 227 if (altsetting == -1) { 228 dev_err(&intf->dev, "cannot find expected altsetting\n"); 229 ret = -ENODEV; 230 goto out; 231 } 232 233 tt->dev = &intf->dev; 234 tt->udev = interface_to_usbdev(intf); 235 tt->rc = rc; 236 237 ret = usb_set_interface(tt->udev, 0, altsetting); 238 if (ret) 239 goto out; 240 241 for (i = 0; i < NUM_URBS; i++) { 242 struct urb *urb = usb_alloc_urb(8, GFP_KERNEL); 243 void *buffer; 244 245 if (!urb) { 246 ret = -ENOMEM; 247 goto out; 248 } 249 250 urb->dev = tt->udev; 251 urb->context = tt; 252 urb->pipe = usb_rcvisocpipe(tt->udev, tt->iso_in_endp); 253 urb->interval = 1; 254 buffer = usb_alloc_coherent(tt->udev, 128, GFP_KERNEL, 255 &urb->transfer_dma); 256 if (!buffer) { 257 usb_free_urb(urb); 258 ret = -ENOMEM; 259 goto out; 260 } 261 urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP | URB_ISO_ASAP; 262 urb->transfer_buffer = buffer; 263 urb->complete = ttusbir_urb_complete; 264 urb->number_of_packets = 8; 265 urb->transfer_buffer_length = 128; 266 267 for (j = 0; j < 8; j++) { 268 urb->iso_frame_desc[j].offset = j * 16; 269 urb->iso_frame_desc[j].length = 16; 270 } 271 272 tt->urb[i] = urb; 273 } 274 275 tt->bulk_urb = usb_alloc_urb(0, GFP_KERNEL); 276 if (!tt->bulk_urb) { 277 ret = -ENOMEM; 278 goto out; 279 } 280 --> 281 tt->bulk_buffer[0] = 0xaa; ^^^^^^^^^^^^^^^^^^ 282 tt->bulk_buffer[1] = 0x01; This email is a free service from the Smatch-CI project [smatch.sf.net]. regards, dan carpenter