ath: dfs_pattern_detector: Avoid open coded arithmetic in memory allocation

kmalloc_array()/kcalloc() should be used to avoid potential overflow when
a multiplication is needed to compute the size of the requested memory.

kmalloc_array() can be used here instead of kcalloc() because the array is
fully initialized in the next 'for' loop.

Finally, 'cd->detectors' is defined as 'struct pri_detector **detectors;'.
So 'cd->detectors' and '*cd->detectors' are both some pointer.
So use a more logical 'sizeof(*cd->detectors)'.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>
Link: https://lore.kernel.org/r/0fbcd32a0384ac1f87c5a3549e505e4becc60226.1640624216.git.christophe.jaillet@wanadoo.fr

drivers/net/wireless/ath/dfs_pattern_detector.c

@@ -197,7 +197,7 @@ static void channel_detector_exit(struct dfs_pattern_detector *dpd,
 static struct channel_detector *
 channel_detector_create(struct dfs_pattern_detector *dpd, u16 freq)
 {
-	u32 sz, i;
+	u32 i;
 	struct channel_detector *cd;
 
 	cd = kmalloc(sizeof(*cd), GFP_ATOMIC);
@@ -206,8 +206,8 @@ channel_detector_create(struct dfs_pattern_detector *dpd, u16 freq)
 
 	INIT_LIST_HEAD(&cd->head);
 	cd->freq = freq;
-	sz = sizeof(cd->detectors) * dpd->num_radar_types;
-	cd->detectors = kzalloc(sz, GFP_ATOMIC);
+	cd->detectors = kmalloc_array(dpd->num_radar_types,
+				      sizeof(*cd->detectors), GFP_ATOMIC);
 	if (cd->detectors == NULL)
 		goto fail;