[PATCH] dtc: Fix NULL pointer use in dtlabel + dtref case

[PATCH] dtc: Fix NULL pointer use in dtlabel + dtref case

[Stephen Boyd]

If we have a construct like this:

	label: &handle {
		...
	};

Running dtc on it will cause a segfault, because we use 'target'
when it could be NULL. Move the add_label() call into the if
statement to fix this potentially bad use of a NULL pointer.

Signed-off-by: Stephen Boyd <stephen.boyd-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
---
 dtc-parser.y | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/dtc-parser.y b/dtc-parser.y
index b2fd4d155839..ca3f5003427c 100644
--- a/dtc-parser.y
+++ b/dtc-parser.y
@@ -171,10 +171,10 @@ devicetree:
 		{
 			struct node *target = get_node_by_ref($1, $3);
 
-			add_label(&target->labels, $2);
-			if (target)
+			if (target) {
+				add_label(&target->labels, $2);
 				merge_nodes(target, $4);
-			else
+			} else
 				ERROR(&@3, "Label or path %s not found", $3);
 			$$ = $1;
 		}
-- 
2.10.0.297.gf6727b0

Re: [PATCH] dtc: Fix NULL pointer use in dtlabel + dtref case

[David Gibson]

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On Wed, Jan 25, 2017 at 11:27:24AM -0800, Stephen Boyd wrote:
> If we have a construct like this:
> 
> 	label: &handle {
> 		...
> 	};
> 
> Running dtc on it will cause a segfault, because we use 'target'
> when it could be NULL. Move the add_label() call into the if
> statement to fix this potentially bad use of a NULL pointer.
> 
> Signed-off-by: Stephen Boyd <stephen.boyd-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>

Looks good, but could you please add a testcase, so we don't make the
same mistake in future.

> ---
>  dtc-parser.y | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/dtc-parser.y b/dtc-parser.y
> index b2fd4d155839..ca3f5003427c 100644
> --- a/dtc-parser.y
> +++ b/dtc-parser.y
> @@ -171,10 +171,10 @@ devicetree:
>  		{
>  			struct node *target = get_node_by_ref($1, $3);
>  
> -			add_label(&target->labels, $2);
> -			if (target)
> +			if (target) {
> +				add_label(&target->labels, $2);
>  				merge_nodes(target, $4);
> -			else
> +			} else
>  				ERROR(&@3, "Label or path %s not found", $3);
>  			$$ = $1;
>  		}

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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