[PATCH][V2][next] rtc: ds1307: check for failed memory allocation on wdt

Colin King
2020-04-02T13:54:30Z

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.
Also move the error exit label "exit" to allow a return statement to
be removed.

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>
---
V2: move error exit label and remove a return statement, thanks to
Walter Harms for spotting this clean up.
---
drivers/rtc/rtc-ds1307.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/drivers/rtc/rtc-ds1307.c b/drivers/rtc/rtc-ds1307.c
index fad042118862..c058b02efb4d 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 */

@@ -1979,10 +1984,7 @@ static int ds1307_probe(struct i2c_client *client,

ds1307_hwmon_register(ds1307);
ds1307_clks_register(ds1307);
- ds1307_wdt_register(ds1307);
-
- return 0;
-
+ err = ds1307_wdt_register(ds1307);
exit:
return err;
}
--
2.25.1