[PATCH 6.1 0832/1146] rtc: class: Fix potential memleak in devm_rtc_allocate_device()

Greg Kroah-Hartman
2022-12-28T16:40:15Z

From: Shang XiaoJing <shangxiaojing@huawei.com>

[ Upstream commit 60da73808298ff2cfa9f165d55eb3d7aa7078601 ]

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: 24d23181e43d ("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 | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c
index e48223c00c67..e5b7b48cffac 100644
--- a/drivers/rtc/class.c
+++ b/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);

--
2.35.1