Commit f48670c3 authored Sep 21, 2023 by Alessandro Carminati Committed by Greg Kroah-Hartman Nov 08, 2023

clk: Sanitize possible_parent_show to Handle Return Value of of_clk_get_parent_name



commit ceb87a361d0b079ecbc7d2831618c19087f304a9 upstream.

In the possible_parent_show function, ensure proper handling of the return
value from of_clk_get_parent_name to prevent potential issues arising from
a NULL return.
The current implementation invokes seq_puts directly on the result of
of_clk_get_parent_name without verifying the return value, which can lead
to kernel panic if the function returns NULL.

This patch addresses the concern by introducing a check on the return
value of of_clk_get_parent_name. If the return value is not NULL, the
function proceeds to call seq_puts, providing the returned value as
argument.
However, if of_clk_get_parent_name returns NULL, the function provides a
static string as argument, avoiding the panic.

Fixes: 1ccc0ddf ("clk: Use seq_puts() in possible_parent_show()")
Reported-by: Philip Daly <pdaly@redhat.com>
Signed-off-by: Alessandro Carminati (Red Hat) <alessandro.carminati@gmail.com>
Link: https://lore.kernel.org/r/20230921073217.572151-1-alessandro.carminati@gmail.com


Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 511f3e9b

drivers/clk/clk.c

+12 −9

Original line number	Diff line number	Diff line
		@@ -3080,6 +3080,7 @@ static void possible_parent_show(struct seq_file s, struct clk_core core,
		unsigned int i, char terminator)
		{
		struct clk_core *parent;
		const char *name = NULL;

		/*
		* Go through the following options to fetch a parent's name.
		@@ -3094,18 +3095,20 @@ static void possible_parent_show(struct seq_file s, struct clk_core core,
		* registered (yet).
		*/
		parent = clk_core_get_parent_by_index(core, i);
		if (parent)
		if (parent) {
		seq_puts(s, parent->name);
		else if (core->parents[i].name)
		} else if (core->parents[i].name) {
		seq_puts(s, core->parents[i].name);
		else if (core->parents[i].fw_name)
		} else if (core->parents[i].fw_name) {
		seq_printf(s, "<%s>(fw)", core->parents[i].fw_name);
		else if (core->parents[i].index >= 0)
		seq_puts(s,
		of_clk_get_parent_name(core->of_node,
		core->parents[i].index));
		else
		seq_puts(s, "(missing)");
		} else {
		if (core->parents[i].index >= 0)
		name = of_clk_get_parent_name(core->of_node, core->parents[i].index);
		if (!name)
		name = "(missing)";

		seq_puts(s, name);
		}

		seq_putc(s, terminator);
		}