ASoC: topology: Fix wrong size check

Dan reported that smatch reports wrong size check and after analysis it
is confirmed that we are comparing wrong value: pointer size instead of
array size. However the check itself is problematic as in UAPI header
there are two fields:

struct snd_soc_tplg_enum_control {
    (...)
    char texts[SND_SOC_TPLG_NUM_TEXTS][SNDRV_CTL_ELEM_ID_NAME_MAXLEN];
    __le32 values[SND_SOC_TPLG_NUM_TEXTS * SNDRV_CTL_ELEM_ID_NAME_MAXLEN / 4];

the texts field is for names and the values one for values assigned to
those named fields, after analysis it becomes clear that there is quite
a lot overhead values than we may possibly name. So instead of changing
check to ARRAY_SIZE(ec->values), as it was first suggested, use
hardcoded value of SND_SOC_TPLG_NUM_TEXTS.

Link: https://lore.kernel.org/alsa-devel/X9B0eDcKy+9B6kZl@mwanda/
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/20201210152541.191728-1-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/soc-topology.c b/sound/soc/soc-topology.c
index e85b52798bc54f5148ce8efc49485c5bfc554cfa..950c45008e245fbf2952bff0f9c986c95d40a8a3 100644 (file)
--- a/sound/soc/soc-topology.c
+++ b/sound/soc/soc-topology.c
@@ -892,10 +892,16 @@ static int soc_tplg_denum_create_values(struct soc_tplg *tplg, struct soc_enum *
 {
        int i;
 
-       if (le32_to_cpu(ec->items) > sizeof(*ec->values))
+       /*
+        * Following "if" checks if we have at most SND_SOC_TPLG_NUM_TEXTS
+        * values instead of using ARRAY_SIZE(ec->values) due to the fact that
+        * it is oversized for its purpose. Additionally it is done so because
+        * it is defined in UAPI header where it can't be easily changed.
+        */
+       if (le32_to_cpu(ec->items) > SND_SOC_TPLG_NUM_TEXTS)
                return -EINVAL;
 
-       se->dobj.control.dvalues = devm_kzalloc(tplg->dev, le32_to_cpu(ec->items) *
+       se->dobj.control.dvalues = devm_kcalloc(tplg->dev, le32_to_cpu(ec->items),
                                           sizeof(u32),
                                           GFP_KERNEL);
        if (!se->dobj.control.dvalues)