Hi,
On Thu, Apr 06, 2023 at 06:28:01AM -0700, Xu Biang wrote:
Smatch Warns: sound/firewire/tascam/tascam-stream.c:493 snd_tscm_stream_start_duplex() warn: missing unwind goto?
The direct return will cause the stream list of "&tscm->domain" unemptied and the session in "tscm" unfinished if amdtp_domain_start() returns with an error.
Fix this by changing the direct return to a goto which will empty the stream list of "&tscm->domain" and finish the session in "tscm".
The snd_tscm_stream_start_duplex() function is called in the prepare callback of PCM. According to "ALSA Kernel API Documentation", the prepare callback of PCM will be called many times at each setup. So, if the "&d->streams" list is not emptied, when the prepare callback is called next time, snd_tscm_stream_start_duplex() will receive -EBUSY from amdtp_domain_add_stream() that tries to add an existing stream to the domain. The error handling code after the "error" label will be executed in this case, and the "&d->streams" list will be emptied. So not emptying the "&d->streams" list will not cause an issue. But it is more efficient and readable to empty it on the first error by changing the direct return to a goto statement.
The session in "tscm" has been begun before amdtp_domain_start(), so it needs to be finished when amdtp_domain_start() fails.
Fixes: c281d46a51e3 ("ALSA: firewire-tascam: support AMDTP domain") Signed-off-by: Xu Biang xubiang@hust.edu.cn Reviewed-by: Dan Carpenter error27@gmail.com
Note that this finding is from static analysis and not tested.
sound/firewire/tascam/tascam-stream.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Indeed. I overlooked it when posting the patch. The bug exists Linux kernel v5.4 or later and the fix should be forward to stable kernels.
Acked-by: Takashi Sakamoto o-takashi@sakamocchi.jp
diff --git a/sound/firewire/tascam/tascam-stream.c b/sound/firewire/tascam/tascam-stream.c index 53e094cc411f..dfe783d01d7d 100644 --- a/sound/firewire/tascam/tascam-stream.c +++ b/sound/firewire/tascam/tascam-stream.c @@ -490,7 +490,7 @@ int snd_tscm_stream_start_duplex(struct snd_tscm *tscm, unsigned int rate) // packet is important for media clock recovery. err = amdtp_domain_start(&tscm->domain, tx_init_skip_cycles, true, true); if (err < 0)
return err;
goto error;if (!amdtp_domain_wait_ready(&tscm->domain, READY_TIMEOUT_MS)) { err = -ETIMEDOUT;
-- 2.17.1
Thanks
Takashi Sakamoto