ASoC: cache: Do the codec->reg_cache zero pionter check

For the snd_soc_cache_init(), the reg_size maybe zero and then the value
of codec->reg_cache, which is alloced via kzalloc, maybe equal to
ZERO_SIZE_PTR. If the reg parameter of snd_soc_cache_write() is large enough,
the cache[idx] = val maybe cause the kernel crash...

So this patch fix this via doing the zero pionter check of it.

Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 7 insertions, 6 deletions

diff --git a/sound/soc/soc-cache.c b/sound/soc/soc-cache.c
index 375dc6dfba4e..bfed3e4c45ff 100644
--- a/sound/soc/soc-cache.c
+++ b/sound/soc/soc-cache.c
@@ -96,8 +96,7 @@ int snd_soc_cache_exit(struct snd_soc_codec *codec)
 {
         dev_dbg(codec->dev, "ASoC: Destroying cache for %s codec\n",
                         codec->name);
-        if (!codec->reg_cache)
-                return 0;
+
         kfree(codec->reg_cache);
         codec->reg_cache = NULL;
         return 0;
@@ -117,8 +116,9 @@ int snd_soc_cache_read(struct snd_soc_codec *codec,
                 return -EINVAL;
 
         mutex_lock(&codec->cache_rw_mutex);
-        *value = snd_soc_get_cache_val(codec->reg_cache, reg,
-                                       codec->driver->reg_word_size);
+        if (!ZERO_OR_NULL_PTR(codec->reg_cache))
+                *value = snd_soc_get_cache_val(codec->reg_cache, reg,
+                                               codec->driver->reg_word_size);
         mutex_unlock(&codec->cache_rw_mutex);
 
         return 0;
@@ -136,8 +136,9 @@ int snd_soc_cache_write(struct snd_soc_codec *codec,
                         unsigned int reg, unsigned int value)
 {
         mutex_lock(&codec->cache_rw_mutex);
-        snd_soc_set_cache_val(codec->reg_cache, reg, value,
-                              codec->driver->reg_word_size);
+        if (!ZERO_OR_NULL_PTR(codec->reg_cache))
+                snd_soc_set_cache_val(codec->reg_cache, reg, value,
+                                      codec->driver->reg_word_size);
         mutex_unlock(&codec->cache_rw_mutex);
 
         return 0;