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SubjectRe: [PATCH][next] rtc: ds1307: check for failed memory allocation on wdt
On 02/04/2020 14:14:41+0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Currently a failed memory allocation will lead to a null pointer
> dereference on point wdt. Fix this by checking for a failed allocation
> and adding error return handling to function ds1307_wdt_register.
>
> Addresses-Coverity: ("Dereference null return")
> Fixes: fd90d48db037 ("rtc: ds1307: add support for watchdog timer on ds1388")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/rtc/rtc-ds1307.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
> index fad042118862..95c5b6facc59 100644
> --- a/drivers/rtc/rtc-ds1307.c
> +++ b/drivers/rtc/rtc-ds1307.c
> @@ -1665,14 +1665,16 @@ static const struct watchdog_ops ds1388_wdt_ops = {
>
> };
>
> -static void ds1307_wdt_register(struct ds1307 *ds1307)
> +static int ds1307_wdt_register(struct ds1307 *ds1307)
> {
> struct watchdog_device *wdt;
>
> if (ds1307->type != ds_1388)
> - return;
> + return 0;
>
> wdt = devm_kzalloc(ds1307->dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
>
> wdt->info = &ds1388_wdt_info;
> wdt->ops = &ds1388_wdt_ops;
> @@ -1683,10 +1685,13 @@ static void ds1307_wdt_register(struct ds1307 *ds1307)
> watchdog_init_timeout(wdt, 0, ds1307->dev);
> watchdog_set_drvdata(wdt, ds1307);
> devm_watchdog_register_device(ds1307->dev, wdt);
> +
> + return 0;
> }
> #else
> -static void ds1307_wdt_register(struct ds1307 *ds1307)
> +static int ds1307_wdt_register(struct ds1307 *ds1307)
> {
> + return 0;
> }
> #endif /* CONFIG_WATCHDOG_CORE */
>
> @@ -1979,9 +1984,9 @@ static int ds1307_probe(struct i2c_client *client,
>
> ds1307_hwmon_register(ds1307);
> ds1307_clks_register(ds1307);
> - ds1307_wdt_register(ds1307);
> + err = ds1307_wdt_register(ds1307);
>
> - return 0;
> + return err;

As the watchdog is optional and the RTC can work properly without the
watchdog driver being compiled, my opinion is that the error should not
be returned.


--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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