[PATCH v2] rtc: class: check return value when calling dev_set_name()

[Yang Yingliang]

I got a null-ptr-deref report when doing fault injection test:

BUG: kernel NULL pointer dereference, address: 0000000000000000
RIP: 0010:strcmp+0xc/0x20
Call Trace:
 __devm_rtc_register_device.cold.7+0x16a/0x2df
 rv3029_probe+0x4b1/0x770 [rtc_rv3029c2]
 rv3029_i2c_probe+0x141/0x180 [rtc_rv3029c2]
 i2c_device_probe+0xa07/0xbb0
 really_probe+0x285/0xc30

If dev_set_name() fails, dev_name() is null, it causes null-ptr-deref,
we need check the return value of dev_set_name().

Reported-by: Hulk Robot <hulkci@xxxxxxxxxx>
Signed-off-by: Yang Yingliang <yangyingliang@xxxxxxxxxx>
---
v2:
  drop some unuseful backtrace in commit message.
---
 drivers/rtc/class.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index f77bc089eb6b..1f18c39a4b82 100644
--- a/drivers/rtc/class.c
+++ b/drivers/rtc/class.c
@@ -363,7 +363,9 @@ struct rtc_device *devm_rtc_allocate_device(struct device *dev)
 
 	rtc->id = id;
 	rtc->dev.parent = dev;
-	dev_set_name(&rtc->dev, "rtc%d", id);
+	err = dev_set_name(&rtc->dev, "rtc%d", id);
+	if (err)
+		return ERR_PTR(err);
 
 	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
 	if (err)
-- 
2.25.1