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| author |   Yang Yingliang <yangyingliang@huawei.com> | 2021-10-11 21:21:14 +0800 |
|---|---|---|
| committer |   Alexandre Belloni <alexandre.belloni@bootlin.com> | 2021-10-15 21:05:33 +0200 |
| commit | 789c1093f02c436b320d78a739f9610c8271cb73 (patch) | |
| tree | 65076af5708f1c12ef9eb2926237bb62ee30800b /drivers/rtc | |
| parent | rtc: m41t80: return NULL rather than a plain 0 integer (diff) | |
| download | linux-dev-789c1093f02c436b320d78a739f9610c8271cb73.tar.xz linux-dev-789c1093f02c436b320d78a739f9610c8271cb73.zip | |
rtc: class: don't call cdev_device_del() when cdev_device_add() failed
I got a null-ptr-deref report when doing fault injection test:
general protection fault, probably for non-canonical address 0xdffffc0000000022: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000110-0x0000000000000117]
RIP: 0010:device_del+0x132/0xdc0
Call Trace:
cdev_device_del+0x1a/0x80
devm_rtc_unregister_device+0x37/0x80
release_nodes+0xc3/0x3b0
If cdev_device_add() fails, 'dev->p' is not set, it causes
null-ptr-deref when calling cdev_device_del(). Registering
character device is optional, we don't return error code
here, so introduce a new flag 'RTC_NO_CDEV' to indicate
if it has character device, cdev_device_del() is called
when this bit is not set.
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20211011132114.3663509-1-yangyingliang@huawei.com
Diffstat (limited to 'drivers/rtc')
| -rw-r--r-- | drivers/rtc/class.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/drivers/rtc/class.c b/drivers/rtc/class.c index f77bc089eb6b..654e921244bf 100644 --- a/drivers/rtc/class.c +++ b/drivers/rtc/class.c @@ -334,7 +334,8 @@ static void devm_rtc_unregister_device(void *data) * letting any rtc_class_open() users access it again */ rtc_proc_del_device(rtc); - cdev_device_del(&rtc->char_dev, &rtc->dev); + if (!test_bit(RTC_NO_CDEV, &rtc->flags)) + cdev_device_del(&rtc->char_dev, &rtc->dev); rtc->ops = NULL; mutex_unlock(&rtc->ops_lock); } @@ -397,12 +398,14 @@ int __devm_rtc_register_device(struct module *owner, struct rtc_device *rtc) rtc_dev_prepare(rtc); err = cdev_device_add(&rtc->char_dev, &rtc->dev); - if (err) + if (err) { + set_bit(RTC_NO_CDEV, &rtc->flags); dev_warn(rtc->dev.parent, "failed to add char device %d:%d\n", MAJOR(rtc->dev.devt), rtc->id); - else + } else { dev_dbg(rtc->dev.parent, "char device (%d:%d)\n", MAJOR(rtc->dev.devt), rtc->id); + } rtc_proc_add_device(rtc); |