Hello Takashi Iwai,
The patch 0b5288f5fe63: "ALSA: ump: Add legacy raw MIDI support" from
May 23, 2023, leads to the following Smatch static checker warning:
sound/core/ump_convert.c:460 do_convert_to_ump()
warn: right shifting more than type allows 8 vs 8
sound/core/ump_convert.c
419 static int do_convert_to_ump(struct snd_ump_endpoint *ump,
420 unsigned char group, unsigned char c, u32 *data)
421 {
422 /* bytes for 0x80-0xf0 */
423 static unsigned char cmd_bytes[8] = {
424 3, 3, 3, 3, 2, 2, 3, 0
425 };
426 /* bytes for 0xf0-0xff */
427 static unsigned char system_bytes[16] = {
428 0, 2, 3, 2, 0, 0, 1, 0, 1, 1, 1, 1, 0, 0, 1, 1
429 };
430 struct ump_cvt_to_ump *cvt = &ump->out_cvts[group];
431 unsigned char bytes;
432
433 if (c == UMP_MIDI1_MSG_SYSEX_START) {
434 cvt->in_sysex = 1;
435 cvt->len = 0;
436 return 0;
437 }
438 if (c == UMP_MIDI1_MSG_SYSEX_END) {
439 if (!cvt->in_sysex)
440 return 0; /* skip */
441 return cvt_legacy_sysex_to_ump(cvt, group, data, true);
442 }
443
444 if ((c & 0xf0) == UMP_MIDI1_MSG_REALTIME) {
445 bytes = system_bytes[c & 0x0f];
446 if (!bytes)
447 return 0; /* skip */
448 if (bytes == 1) {
449 data[0] = ump_compose(UMP_MSG_TYPE_SYSTEM, group, 0, c);
450 return 4;
451 }
452 cvt->buf[0] = c;
453 cvt->len = 1;
454 cvt->cmd_bytes = bytes;
455 cvt->in_sysex = 0; /* abort SysEx */
456 return 0;
457 }
458
459 if (c & 0x80) {
--> 460 bytes = cmd_bytes[(c >> 8) & 7];
^^^^^^
Based on the if statement, it looks like c >> 4 was intended.
461 cvt->buf[0] = c;
462 cvt->len = 1;
463 cvt->cmd_bytes = bytes;
464 cvt->in_sysex = 0; /* abort SysEx */
465 return 0;
466 }
467
468 if (cvt->in_sysex) {
469 cvt->buf[cvt->len++] = c;
470 if (cvt->len == 6)
471 return cvt_legacy_sysex_to_ump(cvt, group, data, false);
472 return 0;
473 }
474
475 if (!cvt->len)
476 return 0;
477
478 cvt->buf[cvt->len++] = c;
479 if (cvt->len < cvt->cmd_bytes)
480 return 0;
481 cvt->len = 1;
482 if ((cvt->buf[0] & 0xf0) == UMP_MIDI1_MSG_REALTIME)
483 return cvt_legacy_system_to_ump(cvt, group, data);
484 return cvt_legacy_cmd_to_ump(ump, cvt, group, data, cvt->cmd_bytes);
485 }
regards,
dan carpenter
