linux-kernel - Re: [RFC PATCH 08/77] dtc: Introduce update_phandles

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aWg4_KIBbUMOdP9C@zatzit>
Date: Thu, 15 Jan 2026 11:46:52 +1100
From: David Gibson <david@...son.dropbear.id.au>
To: Herve Codina <herve.codina@...tlin.com>
Cc: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>,
	Ayush Singh <ayush@...gleboard.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	devicetree-compiler@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, devicetree-spec@...r.kernel.org,
	Hui Pu <hui.pu@...ealthcare.com>,
	Ian Ray <ian.ray@...ealthcare.com>,
	Luca Ceresoli <luca.ceresoli@...tlin.com>,
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Subject: Re: [RFC PATCH 08/77] dtc: Introduce update_phandles_ref()

On Mon, Jan 12, 2026 at 03:18:58PM +0100, Herve Codina wrote:
> With the introduction of FDT_REF_LOCAL dtb tag, a local phandle used
> by a property is identify when a dtb is parsed.
> 
> In order to have consistent internal data, the reference related to this
> phandle usage needs to be updated based on the phandle value.
> 
> This is done by update_phandles_ref().
> 
> Signed-off-by: Herve Codina <herve.codina@...tlin.com>
> ---
>  dtc.c      |  2 ++
>  dtc.h      |  2 ++
>  livetree.c | 38 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 42 insertions(+)
> 
> diff --git a/dtc.c b/dtc.c
> index b3445b7..88f03ff 100644
> --- a/dtc.c
> +++ b/dtc.c
> @@ -333,6 +333,8 @@ int main(int argc, char *argv[])
>  		generate_fixups = 1;
>  	}
>  
> +	update_phandles_ref(dti);
> +
>  	process_checks(force, dti);
>  
>  	if (auto_label_aliases)
> diff --git a/dtc.h b/dtc.h
> index 965321c..351fe41 100644
> --- a/dtc.h
> +++ b/dtc.h
> @@ -345,6 +345,8 @@ void generate_label_tree(struct dt_info *dti, const char *name, bool allocph);
>  void generate_fixups_tree(struct dt_info *dti, const char *name);
>  void generate_local_fixups_tree(struct dt_info *dti, const char *name);
>  
> +void update_phandles_ref(struct dt_info *dti);
> +
>  /* Checks */
>  
>  void parse_checks_option(bool warn, bool error, const char *arg);
> diff --git a/livetree.c b/livetree.c
> index 9b67934..9e30a63 100644
> --- a/livetree.c
> +++ b/livetree.c
> @@ -1158,3 +1158,41 @@ void generate_local_fixups_tree(struct dt_info *dti, const char *name)
>  			"Warning: Preexisting data in %s malformed, some content could not be added.\n",
>  			name);
>  }
> +
> +static void update_phandles_ref_internal(struct dt_info *dti, struct node *node)
> +{
> +	struct node *c;
> +	struct property *prop;
> +	struct marker *m;
> +	struct node *refnode;
> +	cell_t phandle;
> +
> +	for_each_property(node, prop) {
> +		m = prop->val.markers;
> +		for_each_marker_of_type(m, REF_PHANDLE) {
> +			if (m->ref)
> +				continue;

IIUC this means that REF_PHANDLE markers can be missing their ref.
Allowing the markers to be in an incomplete state is a footgun.  If
possible it would be better to fully generate the markers when we
create them.  If not, we should use a different marker type when it's
introduced, and convert it later.

I think what's going on here is one type is saying "you have a
reference, fill in the phandle", the other is saying "you have a
phandle, fill in the reference".  Those seem like they should be
different types to me, even if they can be converted once all the
fixups are applied.

> +
> +			if (m->is_local) {
> +				phandle = propval_cell_n(prop,
> +							 m->offset / sizeof(cell_t));
> +				refnode = get_node_by_phandle(dti->dt, phandle);
> +				if (!refnode)
> +					die("Node not found for phandle 0x%"PRIx32"\n", phandle);
> +
> +				m->ref = refnode->fullpath;
> +				continue;
> +			} else {
> +				die("Found a non local phandle without a reference\n");
> +			}
> +		}
> +	}
> +
> +	for_each_child(node, c)
> +		update_phandles_ref_internal(dti, c);
> +}
> +
> +void update_phandles_ref(struct dt_info *dti)
> +{
> +	update_phandles_ref_internal(dti, dti->dt);
> +}
> -- 
> 2.52.0
> 
> 

-- 
David Gibson (he or they)	| 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

Download attachment "signature.asc" of type "application/pgp-signature" (834 bytes)