From: Julia Lawall julia@diku.dk
If the NULL test on h is needed in snd_harmony_mixer_init, then the dereference should be after the NULL test.
Actually, there is a sequence of calls: snd_harmony_create, then snd_harmony_pcm_init, and then snd_harmony_mixer_init. snd_harmony_create initializes h, but may indeed leave it as NULL. There was no NULL test at the beginning of snd_harmony_pcm_init, so I have added one. The NULL test in snd_harmony_mixer_init is then not necessary, but in case the ordering of the calls changes, I have left it, and moved the dereference after it.
A simplified version of the semantic match that detects this problem is as follows (http://coccinelle.lip6.fr/):
// <smpl> @match exists@ expression x, E; identifier fld; @@
* x->fld ... when != (x = E|&x) * x == NULL // </smpl>
Signed-off-by: Julia Lawall julia@diku.dk
--- sound/parisc/harmony.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/sound/parisc/harmony.c b/sound/parisc/harmony.c index e924492..f47f9e2 100644 --- a/sound/parisc/harmony.c +++ b/sound/parisc/harmony.c @@ -624,6 +624,9 @@ snd_harmony_pcm_init(struct snd_harmony *h) struct snd_pcm *pcm; int err;
+ if (snd_BUG_ON(!h)) + return -EINVAL; + harmony_disable_interrupts(h); err = snd_pcm_new(h->card, "harmony", 0, 1, 1, &pcm); @@ -865,11 +868,12 @@ snd_harmony_mixer_reset(struct snd_harmony *h) static int __devinit snd_harmony_mixer_init(struct snd_harmony *h) { - struct snd_card *card = h->card; + struct snd_card *card; int idx, err;
if (snd_BUG_ON(!h)) return -EINVAL; + card = h->card; strcpy(card->mixername, "Harmony Gain control interface");
for (idx = 0; idx < HARMONY_CONTROLS; idx++) {