ALSA: usb - driver neglects kmalloc return value check and may deref NULL

sound/usb/pcm.c::snd_usb_pcm_check_knot() fails to check the return value
from kmalloc() and may end up dereferencing a null pointer.
The patch below (compile tested only) should take care of that little
problem.

Signed-off-by: Jesper Juhl <jj@chaosbits.net>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

1 files changed, 3 insertions, 1 deletions

diff --git a/sound/usb/pcm.c b/sound/usb/pcm.c
index cff3a3c465d7..4132522ac90f 100644
--- a/sound/usb/pcm.c
+++ b/sound/usb/pcm.c
@@ -676,8 +676,10 @@ static int snd_usb_pcm_check_knot(struct snd_pcm_runtime *runtime,
         if (!needs_knot)
                 return 0;
 
-        subs->rate_list.count = count;
         subs->rate_list.list = kmalloc(sizeof(int) * count, GFP_KERNEL);
+        if (!subs->rate_list.list)
+                return -ENOMEM;
+        subs->rate_list.count = count;
         subs->rate_list.mask = 0;
         count = 0;
         list_for_each_entry(fp, &subs->fmt_list, list) {