lib: check null pointer before taking lock for bitarray

In some function in bitarray.c, we should check the pointer
of bitarry before taking bitarray lock.

In this patch, we move the null-check assert before the use of
the struct to provide better validation than a crash.

Signed-off-by: TaiJu Wu <[email protected]>

lib/utils/bitarray.c

@@ -218,11 +218,11 @@ int sys_bitarray_popcount_region(sys_bitarray_t *bitarray, size_t num_bits, size
 	struct bundle_data bd;
 	int ret;
 
-	key = k_spin_lock(&bitarray->lock);
-
 	__ASSERT_NO_MSG(bitarray != NULL);
 	__ASSERT_NO_MSG(bitarray->num_bits > 0);
 
+	key = k_spin_lock(&bitarray->lock);
+
 	if (num_bits == 0 || offset + num_bits > bitarray->num_bits) {
 		ret = -EINVAL;
 		goto out;
@@ -266,14 +266,15 @@ int sys_bitarray_xor(sys_bitarray_t *dst, sys_bitarray_t *other, size_t num_bits
 	size_t idx;
 	struct bundle_data bd;
 
-	key_dst = k_spin_lock(&dst->lock);
-	key_other = k_spin_lock(&other->lock);
-
 	__ASSERT_NO_MSG(dst != NULL);
 	__ASSERT_NO_MSG(dst->num_bits > 0);
 	__ASSERT_NO_MSG(other != NULL);
 	__ASSERT_NO_MSG(other->num_bits > 0);
 
+	key_dst = k_spin_lock(&dst->lock);
+	key_other = k_spin_lock(&other->lock);
+
+
 	if (dst->num_bits != other->num_bits) {
 		ret = -EINVAL;
 		goto out;
@@ -322,11 +323,11 @@ int sys_bitarray_set_bit(sys_bitarray_t *bitarray, size_t bit)
 	int ret;
 	size_t idx, off;
 
-	key = k_spin_lock(&bitarray->lock);
-
 	__ASSERT_NO_MSG(bitarray != NULL);
 	__ASSERT_NO_MSG(bitarray->num_bits > 0);
 
+	key = k_spin_lock(&bitarray->lock);
+
 	if (bit >= bitarray->num_bits) {
 		ret = -EINVAL;
 		goto out;