linux-kernel - Re: [PATCH v1] dpaa2-switch: fix memory leak of dpaa2_switch_acl_entry

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Date:   Tue, 1 Mar 2022 17:41:20 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Yeqi Fu <fufuyqqqqqq@...il.com>
Cc:     ioana.ciornei@....com, davem@...emloft.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Yongzhi Liu <lyz_cs@....edu.cn>
Subject: Re: [PATCH v1] dpaa2-switch: fix memory leak of
 dpaa2_switch_acl_entry_add

On Tue,  1 Mar 2022 22:15:44 +0800 Yeqi Fu wrote:
> @@ -142,6 +143,7 @@ int dpaa2_switch_acl_entry_add(struct dpaa2_switch_filter_block *filter_block,
>  			 DMA_TO_DEVICE);
>  	if (err) {
>  		dev_err(dev, "dpsw_acl_add_entry() failed %d\n", err);
> +		kfree(cmd_buff);
>  		return err;
>  	}

With more context:

                return -EFAULT;
        }
 
        err = dpsw_acl_add_entry(ethsw->mc_io, 0, ethsw->dpsw_handle,
                                 filter_block->acl_id, acl_entry_cfg);
 
        dma_unmap_single(dev, acl_entry_cfg->key_iova, sizeof(cmd_buff),
                         DMA_TO_DEVICE);
        if (err) {
                dev_err(dev, "dpsw_acl_add_entry() failed %d\n", err);
+               kfree(cmd_buff);
                return err;
        }
 
        kfree(cmd_buff);
 
        return 0;
 }

Here we see unmap is "pulled up" above the error check, same thing can
be done with the kfree(). Otherwise it looks slightly weird - the
buffer unmap and kfree are conceptually part of releasing the buffer,
yet they are split across the paths.