rtc: class: Fix potential memleak in devm_rtc_allocate_device()

[ Upstream commit 60da738 ]

devm_rtc_allocate_device() will alloc a rtc_device first, and then run
dev_set_name(). If dev_set_name() failed, the rtc_device will memleak.
Move devm_add_action_or_reset() in front of dev_set_name() to prevent
memleak.

unreferenced object 0xffff888110a53000 (size 2048):
  comm "python3", pid 470, jiffies 4296078308 (age 58.882s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 08 30 a5 10 81 88 ff ff  .........0......
    08 30 a5 10 81 88 ff ff 00 00 00 00 00 00 00 00  .0..............
  backtrace:
    [<000000004aac0364>] kmalloc_trace+0x21/0x110
    [<000000000ff02202>] devm_rtc_allocate_device+0xd4/0x400
    [<000000001bdf5639>] devm_rtc_device_register+0x1a/0x80
    [<00000000351bf81c>] rx4581_probe+0xdd/0x110 [rtc_rx4581]
    [<00000000f0eba0ae>] spi_probe+0xde/0x130
    [<00000000bff89ee8>] really_probe+0x175/0x3f0
    [<00000000128e8d84>] __driver_probe_device+0xe6/0x170
    [<00000000ee5bf913>] device_driver_attach+0x32/0x80
    [<00000000f3f28f92>] bind_store+0x10b/0x1a0
    [<000000009ff812d8>] drv_attr_store+0x49/0x70
    [<000000008139c323>] sysfs_kf_write+0x8d/0xb0
    [<00000000b6146e01>] kernfs_fop_write_iter+0x214/0x2d0
    [<00000000ecbe3895>] vfs_write+0x61a/0x7d0
    [<00000000aa2196ea>] ksys_write+0xc8/0x190
    [<0000000046a600f5>] do_syscall_64+0x37/0x90
    [<00000000541a336f>] entry_SYSCALL_64_after_hwframe+0x63/0xcd

Fixes: 24d2318 ("rtc: class: check return value when calling dev_set_name()")
Signed-off-by: Shang XiaoJing <shangxiaojing@huawei.com>
Reviewed-by: Yang Yingliang <yangyingliang@huawei.com>
Link: https://lore.kernel.org/r/20221110090810.11225-1-shangxiaojing@huawei.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

drivers/rtc/class.c

@@ -374,11 +374,11 @@ struct rtc_device *devm_rtc_allocate_device(struct device *dev)
 
 	rtc->id = id;
 	rtc->dev.parent = dev;
-	err = dev_set_name(&rtc->dev, "rtc%d", id);
+	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
 	if (err)
 		return ERR_PTR(err);
 
-	err = devm_add_action_or_reset(dev, devm_rtc_release_device, rtc);
+	err = dev_set_name(&rtc->dev, "rtc%d", id);
 	if (err)
 		return ERR_PTR(err);