Hi,
Static analysis with Coverity on linux-next has detected an uninitialized variable issue with the following commit:
commit 481f17c41803985446fd12887b2c042f9c43b0d5 Author: Takashi Iwai tiwai@suse.de Date: Tue May 18 17:21:12 2021 +0200
ALSA: usb-audio: Handle error for the current selector gracefully
The branching is a bit convoluted and we end up with variable cur not being initialized. Analysis is as follows:
254static int __uac_clock_find_source(struct snd_usb_audio *chip, 255 const struct audioformat *fmt, int entity_id, 256 unsigned long *visited, bool validate) 257{ 258 union uac23_clock_source_desc *source; 259 union uac23_clock_selector_desc *selector; 260 union uac23_clock_multiplier_desc *multiplier;
1. var_decl: Declaring variable cur without initializer.
261 int ret, i, cur, err, pins, clock_id; 262 const u8 *sources; 263 int proto = fmt->protocol; 264 265 entity_id &= 0xff; 266
2. Condition test_and_set_bit(entity_id, visited), taking false branch.
267 if (test_and_set_bit(entity_id, visited)) { 268 usb_audio_warn(chip, 269 "%s(): recursive clock topology detected, id %d.\n", 270 __func__, entity_id); 271 return -EINVAL; 272 } 273 274 /* first, see if the ID we're looking for is a clock source already */ 275 source = snd_usb_find_clock_source(chip, entity_id, proto);
3. Condition source, taking false branch.
276 if (source) { 277 entity_id = GET_VAL(source, proto, bClockID); 278 if (validate && !uac_clock_source_is_valid(chip, fmt, 279 entity_id)) { 280 usb_audio_err(chip, 281 "clock source %d is not valid, cannot use\n", 282 entity_id); 283 return -ENXIO; 284 } 285 return entity_id; 286 } 287 288 selector = snd_usb_find_clock_selector(chip, entity_id, proto);
4. Condition selector, taking true branch. 289 if (selector) { 5. Condition proto == 48, taking true branch. 290 pins = GET_VAL(selector, proto, bNrInPins); 6. Condition proto == 48, taking true branch. 291 clock_id = GET_VAL(selector, proto, bClockID); 7. Condition proto == 48, taking true branch. 292 sources = GET_VAL(selector, proto, baCSourceID); 293 8. Condition pins == 1, taking false branch.
294 if (pins == 1) { 295 ret = 1; 296 goto find_source; 297 } 298 299 /* the entity ID we are looking for is a selector. 300 * find out what it currently selects */ 301 ret = uac_clock_selector_get_val(chip, clock_id);
9. Condition ret < 0, taking true branch.
302 if (ret < 0) {
10. Condition !chip->autoclock, taking false branch.
303 if (!chip->autoclock) 304 return ret;
11. Jumping to label find_others.
305 goto find_others; 306 } 307 308 /* Selector values are one-based */ 309 310 if (ret > pins || ret < 1) { 311 usb_audio_err(chip, 312 "%s(): selector reported illegal value, id %d, ret %d\n", 313 __func__, clock_id, ret); 314 315 if (!chip->autoclock) 316 return -EINVAL; 317 ret = 0; 318 goto find_others; 319 } 320 321 find_source: 322 cur = ret; 323 ret = __uac_clock_find_source(chip, fmt, 324 sources[ret - 1], 325 visited, validate); 326 if (ret > 0) { 327 err = uac_clock_selector_set_val(chip, entity_id, cur); 328 if (err < 0) 329 return err; 330 } 331 332 if (!validate || ret > 0 || !chip->autoclock) 333 return ret; 334 335 find_others: 336 /* The current clock source is invalid, try others. */ 12. Condition i <= pins, taking true branch. 337 for (i = 1; i <= pins; i++) {
Uninitialized scalar variable (UNINIT)
13. uninit_use: Using uninitialized value cur.
338 if (i == cur) 339 continue; 340
Colin