On Tue, 10 Sep 2019 16:46:04 +0200, Takashi Iwai wrote:
On Tue, 10 Sep 2019 16:23:59 +0200, Peter Ujfalusi wrote:
On 10/09/2019 15.07, Takashi Iwai wrote:
On Fri, 06 Sep 2019 07:55:24 +0200, Peter Ujfalusi wrote:
Some tools use the snd_pcm_info_get_name() to try to identify PCMs or for other purposes.
Currently it is left empty with the dmaengine-pcm, in this case copy the pcm->id string as pcm->name.
For example IGT is using this to find the HDMI PCM for testing audio on it.
Signed-off-by: Peter Ujfalusi peter.ujfalusi@ti.com Reported-by: Arthur She arthur.she@linaro.org
Hi,
this was actually reported for 4.14 kernel with omap-pcm (replaced by sdma-pcm in v4.18), since then we only use the generic dmaengine PCM but the same issue applies today.
Regards, Peter
sound/soc/soc-generic-dmaengine-pcm.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c index 748f5f641002..d93db2c2b527 100644 --- a/sound/soc/soc-generic-dmaengine-pcm.c +++ b/sound/soc/soc-generic-dmaengine-pcm.c @@ -306,6 +306,12 @@ static int dmaengine_pcm_new(struct snd_soc_pcm_runtime *rtd)
if (!dmaengine_pcm_can_report_residue(dev, pcm->chan[i])) pcm->flags |= SND_DMAENGINE_PCM_FLAG_NO_RESIDUE;
if (rtd->pcm->streams[i].pcm->name[0] == '\0') {strncpy(rtd->pcm->streams[i].pcm->name,rtd->pcm->streams[i].pcm->id,sizeof(rtd->pcm->streams[i].pcm->name));}Any reason to use strncpy() instead of strscpy()? After merging Mark's branch, I got a compile warning like: sound/soc/soc-generic-dmaengine-pcm.c:311:4: warning: 'strncpy' accessing 80 bytes at offsets 88 and 24 may overlap up to 0 bytes at offset [9223372036854775807, -9223372036854775808] [-Wrestrict]
I have not seen such a warning. 'may overlap up to 0 bytes' ? snd_pcm_info { ... unsigned char id[64]; /* ID (user selectable) */ unsigned char name[80]; /* name of this device */ unsigned char subname[32]; /* subdevice name */ ... };
and strncpy() supposed to be something like this: char * strncpy(char *dest, const char *src, size_t n) { size_t i;
for (i = 0; i < n && src[i] != '\0'; i++) dest[i] = src[i]; for ( ; i < n; i++) dest[i] = '\0';
return dest; }
I can see if I can get my compilers to show the warning and try strscpy() if it helps on it.
strncpy() doesn't guarantee the string termination if you pass the exact buffer size. Better to use strscpy() in such a case.
On the second thought, if pcm->id isn't NULL-terminated, it would result in OOB access. So, if strncpy() usage is just to guarantee for the zero-fill, that's OK, to ignore as a possibly spurious old gcc warning...
Takashi