The mlxsw_sp_acl_rulei_create() function is supposed to return an error
pointer from mlxsw_afa_block_create().  The problem is that these
functions both return NULL instead of error pointers.  Half the callers
expect NULL and half expect error pointers so it could lead to a NULL
dereference on failure.
This patch changes both of them to return error pointers and changes all
the callers which checked for NULL to check for IS_ERR() instead.
Fixes: 4cda7d8d7098 ("mlxsw: core: Introduce flexible actions support")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 
        block = kzalloc(sizeof(*block), GFP_KERNEL);
        if (!block)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
        INIT_LIST_HEAD(&block->resource_list);
        block->afa = mlxsw_afa;
 
        mlxsw_afa_set_destroy(block->first_set);
 err_first_set_create:
        kfree(block);
-       return NULL;
+       return ERR_PTR(-ENOMEM);
 }
 EXPORT_SYMBOL(mlxsw_afa_block_create);
 
 
         * to be written using PEFA register to all indexes for all regions.
         */
        afa_block = mlxsw_afa_block_create(mlxsw_sp->afa);
-       if (!afa_block) {
-               err = -ENOMEM;
+       if (IS_ERR(afa_block)) {
+               err = PTR_ERR(afa_block);
                goto err_afa_block;
        }
        err = mlxsw_afa_block_continue(afa_block);
 
 
        rulei = kzalloc(sizeof(*rulei), GFP_KERNEL);
        if (!rulei)
-               return NULL;
+               return ERR_PTR(-ENOMEM);
 
        if (afa_block) {
                rulei->act_block = afa_block;
 
        int err;
 
        afa_block = mlxsw_afa_block_create(mlxsw_sp->afa);
-       if (!afa_block)
-               return ERR_PTR(-ENOMEM);
+       if (IS_ERR(afa_block))
+               return afa_block;
 
        err = mlxsw_afa_block_append_allocated_counter(afa_block,
                                                       counter_index);