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Message-ID: <fc8023b435f78e02c96fecbe8e7599ee.sboyd@kernel.org>
Date: Thu, 07 Sep 2023 15:33:25 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Alessandro Carminati <alessandro.carminati@...il.com>
Cc: Philip Daly <pdaly@...hat.com>,
Michael Turquette <mturquette@...libre.com>,
linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Sanitize possible_parent_show to Handle Return Value of of_clk_get_parent_name
Quoting Alessandro Carminati (2023-09-07 07:15:36)
> this is a gentle ping
>
I couldn't read your email because it was sent to nobody
(unlisted-recipients). Can you resend with a proper To: line?
>
> Il giorno mar 22 ago 2023 alle ore 15:49 Alessandro Carminati
> <alessandro.carminati@...il.com> ha scritto:
> >
> > 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
Use of_clk_get_parent_name() to signify that it is a function.
> > 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.
> >
> > Reported-by: Philip Daly <pdaly@...hat.com>
> > Signed-off-by: Alessandro Carminati (Red Hat) <alessandro.carminati@...il.com>
> > ---
It needs a Fixes tag.
> > drivers/clk/clk.c | 11 ++++++-----
> > 1 file changed, 6 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index c249f9791ae8..ab999644e185 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -3416,6 +3416,7 @@ static void possible_parent_show(struct seq_file *s, struct clk_core *core,
> > unsigned int i, char terminator)
> > {
> > struct clk_core *parent;
> > + const char *tmp;
> >
> > /*
> > * Go through the following options to fetch a parent's name.
> > @@ -3436,12 +3437,12 @@ static void possible_parent_show(struct seq_file *s, struct clk_core *core,
> > seq_puts(s, core->parents[i].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
> > + else if (core->parents[i].index >= 0) {
> > + tmp = of_clk_get_parent_name(core->of_node, core->parents[i].index);
> > + seq_puts(s, tmp ? tmp : "(none)");
How about using seq_printf("%s", ...) instead? That should print out
"(null)" in the case that it is NULL, instead of "(none)" and it is a
one line change.
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