On Thu, 25 May 2023 10:00:10 +0200,
Dan Carpenter wrote:
>
> 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.
Right, currently it's a bogus value. I'll submit the fix patch.
Thanks!
Takashi
