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Subject: Re: [PATCH] of: overlay: add_changeset_property() memory leak
From:   Frank Rowand <frowand.list@gmail.com>
To:     Rob Herring <robh+dt@kernel.org>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        pantelis.antoniou@konsulko.com,
        Pantelis Antoniou <panto@antoniou-consulting.com>
Cc:     devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
        Vincent Whitchurch <rabinv@axis.com>, geert@linux-m68k.org,
        Alan Tull <atull@kernel.org>
References: <1574363816-13981-1-git-send-email-frowand.list@gmail.com>
Message-ID: <9eda204f-aaa0-54a1-83eb-a012ddeeaac3@gmail.com>
Date:   Thu, 21 Nov 2019 13:20:21 -0600
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Hi Vincent,

On 11/21/19 1:16 PM, frowand.list@gmail.com wrote:
> From: Frank Rowand <frank.rowand@sony.com>
> 
> No changeset entries are created for #address-cells and #size-cells
> properties, but the duplicated properties are never freed.  This
> results in a memory leak which is detected by kmemleak:
> 
>  unreferenced object 0x85887180 (size 64):
>    backtrace:
>      kmem_cache_alloc_trace+0x1fb/0x1fc
>      __of_prop_dup+0x25/0x7c
>      add_changeset_property+0x17f/0x370
>      build_changeset_next_level+0x29/0x20c
>      of_overlay_fdt_apply+0x32b/0x6b4
>      ...
> 
> Fixes: 6f75118800acf77f8 ("of: overlay: validate overlay properties #address-cells and #size-cells")
> Reported-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
> Signed-off-by: Frank Rowand <frank.rowand@sony.com>
> ---
>  drivers/of/overlay.c | 37 ++++++++++++++++++++-----------------
>  1 file changed, 20 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
> index c423e94baf0f..9617b7df7c4d 100644
> --- a/drivers/of/overlay.c
> +++ b/drivers/of/overlay.c
> @@ -305,7 +305,6 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>  {
>  	struct property *new_prop = NULL, *prop;
>  	int ret = 0;
> -	bool check_for_non_overlay_node = false;
>  
>  	if (target->in_livetree)
>  		if (!of_prop_cmp(overlay_prop->name, "name") ||
> @@ -318,6 +317,25 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>  	else
>  		prop = NULL;
>  
> +	if (prop) {
> +		if (!of_prop_cmp(prop->name, "#address-cells")) {
> +			if (!of_prop_val_eq(prop, overlay_prop)) {
> +				pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
> +				       target->np);
> +				ret = -EINVAL;
> +			}
> +			return ret;
> +
> +		} else if (!of_prop_cmp(prop->name, "#size-cells")) {
> +			if (!of_prop_val_eq(prop, overlay_prop)) {
> +				pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
> +				       target->np);
> +				ret = -EINVAL;
> +			}
> +			return ret;
> +		}
> +	}
> +
>  	if (is_symbols_prop) {
>  		if (prop)
>  			return -EINVAL;
> @@ -330,33 +348,18 @@ static int add_changeset_property(struct overlay_changeset *ovcs,
>  		return -ENOMEM;
>  
>  	if (!prop) {
> -		check_for_non_overlay_node = true;
>  		if (!target->in_livetree) {
>  			new_prop->next = target->np->deadprops;
>  			target->np->deadprops = new_prop;
>  		}
>  		ret = of_changeset_add_property(&ovcs->cset, target->np,
>  						new_prop);
> -	} else if (!of_prop_cmp(prop->name, "#address-cells")) {
> -		if (!of_prop_val_eq(prop, new_prop)) {
> -			pr_err("ERROR: changing value of #address-cells is not allowed in %pOF\n",
> -			       target->np);
> -			ret = -EINVAL;
> -		}
> -	} else if (!of_prop_cmp(prop->name, "#size-cells")) {
> -		if (!of_prop_val_eq(prop, new_prop)) {
> -			pr_err("ERROR: changing value of #size-cells is not allowed in %pOF\n",
> -			       target->np);
> -			ret = -EINVAL;
> -		}
>  	} else {
> -		check_for_non_overlay_node = true;
>  		ret = of_changeset_update_property(&ovcs->cset, target->np,
>  						   new_prop);
>  	}
>  
> -	if (check_for_non_overlay_node &&
> -	    !of_node_check_flag(target->np, OF_OVERLAY))
> +	if (!of_node_check_flag(target->np, OF_OVERLAY))
>  		pr_err("WARNING: memory leak will occur if overlay removed, property: %pOF/%s\n",
>  		       target->np, new_prop->name);
>  
> 

Can you please check whether this patch fixes the memleak that you
found and fixed in "[PATCH 1/2] of: overlay: fix properties memory leak"?

Thanks,

Frank