pcm: dshare - fix shared memory pointer check

Currently shared memory pointer is initialized to 0 and set to -1
in some, but not in all error paths.
In cleanup path of open the shm pointer is only compared to be non-NULL
before dereferencing it which leads to SEGFAULT in case it was set to -1.

This patch initializes pointer to -1 to have a unique identification
for invalid pointer and also checks for pointer being not -1 on
access in cleanup path.

Signed-off-by: Vanitha Channaiah <vanitha.channaiah@in.bosch.com>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

diff --git a/src/pcm/pcm_dshare.c b/src/pcm/pcm_dshare.c
index dccb137be25399c67c8d9d0b326ec45086576399..1ef5cde4dc02032616233653d7137f61c97a67da 100644 (file)
--- a/src/pcm/pcm_dshare.c
+++ b/src/pcm/pcm_dshare.c
@@ -719,6 +719,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
        dshare->tstamp_type = opts->tstamp_type;
        dshare->semid = -1;
        dshare->shmid = -1;
+       dshare->shmptr = (void *) -1;
 
        ret = snd_pcm_new(&pcm, dshare->type = SND_PCM_TYPE_DSHARE, name, stream, mode);
        if (ret < 0)
@@ -875,7 +876,7 @@ int snd_pcm_dshare_open(snd_pcm_t **pcmp, const char *name,
        return 0;
        
  _err:
-       if (dshare->shmptr)
+       if (dshare->shmptr != (void *) -1)
                dshare->shmptr->u.dshare.chn_mask &= ~dshare->u.dshare.chn_mask;
        if (dshare->timer)
                snd_timer_close(dshare->timer);