[alsa-devel] Segmentation Fault in snd_pcm_rate_hw_free()

[Takashi Iwai]

On Tue, 04 Aug 2015 17:02:26 +0200,
Valentin Corfu wrote:
> 
> 
> 
> On 04.08.2015 17:53, Takashi Iwai wrote:
> > On Tue, 04 Aug 2015 16:08:30 +0200,
> > Valentin Corfu wrote:
> >> Hello ALSA developers,
> >>
> >> I observed one segmentation fault in snd_pcm_rate_hw_free() function,
> >> with the following BT:
> >>
> >> (gdb) up
> >> #1  0xb7554cc1 in raise (sig=6) at
> >> ../nptl/sysdeps/unix/sysv/linux/raise.c:64
> >> 64        return INLINE_SYSCALL (tgkill, 3, pid, selftid, sig);
> >> (gdb)
> >> #2  0xb75580ee in abort () at abort.c:92
> >> 92            raise (SIGABRT);
> >> (gdb)
> >> #3  0xb758a7dd in __libc_message (do_abort=2,
> >>       fmt=0xb766053c "*** glibc detected *** %s: %s: 0x%s ***\n")
> >>       at ../sysdeps/unix/sysv/linux/libc_fatal.c:189
> >> 189           abort ();
> >> (gdb)
> >> #4  0xb7594a71 in malloc_printerr (action=<value optimized out>,
> >>       str=<value optimized out>, ptr=0x969ae98) at malloc.c:6283
> >> 6283          __libc_message (action & 2,
> >> (gdb)
> >> #5  0xb759636b in _int_free (av=<value optimized out>, p=0x969ae90)
> >>       at malloc.c:4795
> >> 4795          malloc_printerr (check_action, errstr, chunk2mem(p));
> >> (gdb)
> >> #6  0xb75994bd in __libc_free (mem=0x969ae98) at malloc.c:3738
> >> 3738      _int_free(ar_ptr, p);
> >> (gdb)
> >> #7  0xb76f3a81 in snd_pcm_rate_hw_free (pcm=0x9685d78) at pcm_rate.c:341
> >> 341                     free(rate->pareas[0].addr);
> > Could you check the content of rate->pareas[0] via gdb?
> (gdb) frame 7
> #7  0xb76f3a81 in snd_pcm_rate_hw_free (pcm=0x9685d78) at pcm_rate.c:341
> 341                     free(rate->pareas[0].addr);
> (gdb) print rate->pareas[0]
> $1 = {addr = 0x969ae98, first = 0, step = 16}
> (gdb) print rate->pareas[0].addr
> $2 = (void *) 0x969ae98

And accessing to pareas[0].addr is OK?  This is a temporary sample
buffer allocated in alsa-lib rate plugin.


> >> (gdb)
> >> #8  0xb76d045b in snd_pcm_hw_free (pcm=0x9685d78) at pcm.c:858
> >> 858             err = pcm->ops->hw_free(pcm->op_arg);
> >> (gdb)
> >> #9  0xb76f826e in snd_pcm_plug_hw_free (pcm=0x96856b0) at pcm_plug.c:1046
> >> 1046            int err = snd_pcm_hw_free(slave);
> >> (gdb)
> >> #10 0xb76d045b in snd_pcm_hw_free (pcm=0x96856b0) at pcm.c:858
> >> 858             err = pcm->ops->hw_free(pcm->op_arg);
> >> (gdb)
> >> #11 0x080492ad in main ()
> >>
> >>
> >> Could you please give me some hints how to solve this issue?
> >>
> >> I can provide you more info or the test application, if needed.
> >> I can see the issue every time, and I also checked with latest version
> >> of alsa-lib but I got the same results.
> > I don't know of such an error, so far.
> > It smells like some memory corruption to me.
> >
> > If a test case is a simple code, tracking the bug would be easy...
> I have paste it here:
> http://pastebin.com/WJDTz6cE

It works fine on my system.  How is your PCM setup?  Does the same
problem occur for "plughw" PCM, too?  Also, no external PCM rate
plugin is involved?


Takashi