From: Saravana Kannan <saravanak@google.com>
To: Tudor Ambarus <tudor.ambarus@microchip.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
"Rafael J. Wysocki" <rafael@kernel.org>,
Michael Turquette <mturquette@baylibre.com>,
Stephen Boyd <sboyd@kernel.org>,
nsaenz@kernel.org, maxime@cerno.tech,
Kevin Hilman <khilman@kernel.org>,
Ulf Hansson <ulf.hansson@linaro.org>,
"Brown, Len" <len.brown@intel.com>, Pavel Machek <pavel@ucw.cz>,
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Frank Rowand <frowand.list@gmail.com>,
Marc Zyngier <maz@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Geert Uytterhoeven <geert@linux-m68k.org>,
Nicolas Saenz Julienne <nsaenzjulienne@suse.de>,
Guenter Roeck <linux@roeck-us.net>,
guillaume.tucker@collabora.com,
linux-clk <linux-clk@vger.kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
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"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
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"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS
<devicetre e@vger.kernel.org>,
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Android Kernel Team <kernel-team@android.com>,
linux-rpi-kernel" <linux-rpi-kernel@lists.infradead.org>,
Marek Szyprowski <m.szyprowski@samsung.com>
Subject: Re: [PATCH v2] clk: Skip clk provider registration when np is NULL
Date: Mon, 26 Apr 2021 11:17:44 -0700 [thread overview]
Message-ID: <CAGETcx9LgyX-D1E0bb-JW=G6TTvr-KC+1-733uWppzGZnYaoxg@mail.gmail.com> (raw)
In-Reply-To: <20210426065618.588144-1-tudor.ambarus@microchip.com>
On Sun, Apr 25, 2021 at 11:56 PM Tudor Ambarus
<tudor.ambarus@microchip.com> wrote:
>
> commit 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
> revealed that clk/bcm/clk-raspberrypi.c driver calls
> devm_of_clk_add_hw_provider(), with a NULL dev->of_node, which resulted in a
> NULL pointer dereference in of_clk_add_hw_provider() when calling
> fwnode_dev_initialized().
>
> Returning 0 is reducing the if conditions in driver code and is being
> consistent with the CONFIG_OF=n inline stub that returns 0 when CONFIG_OF
> is disabled. The downside is that drivers will maybe register clkdev lookups
> when they don't need to and waste some memory.
>
> Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
> Fixes: 6579c8d97ad7 ("clk: Mark fwnodes when their clock provider is added")
> Fixes: 3c9ea42802a1 ("clk: Mark fwnodes when their clock provider is added/removed")
> Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
> Reviewed-by: Stephen Boyd <sboyd@kernel.org>
> ---
Reviewed-by: Saravana Kannan <saravanak@google.com>
-Saravana
> v2:
> - s/return 0;/return; in void of_clk_del_provider()
> - add second fixes tag and Stephen's R-b tag
> The opinions on whether to return an error or zero were split. Returning 0
> and skipping the logic was considered safer as we don't know for sure if
> other drivers are affected. See:
> https://lore.kernel.org/lkml/d24bebc5-0f78-021f-293f-e58defa32531@samsung.com/
> https://lore.kernel.org/lkml/20210423171335.262316-1-tudor.ambarus@microchip.com/
>
> drivers/clk/clk.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
>
> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> index a3b30f7de2ef..b47460b40d14 100644
> --- a/drivers/clk/clk.c
> +++ b/drivers/clk/clk.c
> @@ -4552,6 +4552,9 @@ int of_clk_add_provider(struct device_node *np,
> struct of_clk_provider *cp;
> int ret;
>
> + if (!np)
> + return 0;
> +
> cp = kzalloc(sizeof(*cp), GFP_KERNEL);
> if (!cp)
> return -ENOMEM;
> @@ -4591,6 +4594,9 @@ int of_clk_add_hw_provider(struct device_node *np,
> struct of_clk_provider *cp;
> int ret;
>
> + if (!np)
> + return 0;
> +
> cp = kzalloc(sizeof(*cp), GFP_KERNEL);
> if (!cp)
> return -ENOMEM;
> @@ -4688,6 +4694,9 @@ void of_clk_del_provider(struct device_node *np)
> {
> struct of_clk_provider *cp;
>
> + if (!np)
> + return;
> +
> mutex_lock(&of_clk_mutex);
> list_for_each_entry(cp, &of_clk_providers, link) {
> if (cp->node == np) {
> --
> 2.25.1
>
next prev parent reply other threads:[~2021-04-26 18:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-26 6:56 [PATCH v2] clk: Skip clk provider registration when np is NULL Tudor Ambarus
2021-04-26 18:17 ` Saravana Kannan [this message]
2021-04-27 14:57 ` nicolas saenz julienne
2021-05-10 19:36 ` Guenter Roeck
2021-05-11 7:11 ` Greg KH
2021-05-10 20:20 ` Nathan Chancellor
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