From 789c1093f02c436b320d78a739f9610c8271cb73 Mon Sep 17 00:00:00 2001 From: Yang Yingliang Date: Mon, 11 Oct 2021 21:21:14 +0800 Subject: 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 Signed-off-by: Yang Yingliang Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20211011132114.3663509-1-yangyingliang@huawei.com --- include/linux/rtc.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/rtc.h') diff --git a/include/linux/rtc.h b/include/linux/rtc.h index bd611e26291d..354e0843ab17 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -80,6 +80,7 @@ struct rtc_timer { /* flags */ #define RTC_DEV_BUSY 0 +#define RTC_NO_CDEV 1 struct rtc_device { struct device dev; -- cgit v1.2.3 From 0d20e9fb1262b1f9ac895b287db892bc75b05b84 Mon Sep 17 00:00:00 2001 From: Alexandre Belloni Date: Mon, 18 Oct 2021 17:19:31 +0200 Subject: rtc: add BSM parameter BSM or Backup Switch Mode is a common feature on RTCs, allowing to select how the RTC will decide when to switch from its primary power supply to the backup power supply. It is necessary to be able to set it from userspace as there are uses cases where it has to be done dynamically. Supported values are: RTC_BSM_DISABLED: disabled RTC_BSM_DIRECT: switching will happen as soon as Vbackup > Vdd RTC_BSM_LEVEL: switching will happen around a threshold, usually with an hysteresis RTC_BSM_STANDBY: switching will not happen until Vdd > Vbackup, this is useful to ensure the RTC doesn't draw any power until the device is first powered on. Signed-off-by: Alexandre Belloni Link: https://lore.kernel.org/r/20211018151933.76865-6-alexandre.belloni@bootlin.com --- drivers/rtc/dev.c | 10 ++++++++-- include/linux/rtc.h | 2 ++ include/uapi/linux/rtc.h | 9 ++++++++- 3 files changed, 18 insertions(+), 3 deletions(-) (limited to 'include/linux/rtc.h') diff --git a/drivers/rtc/dev.c b/drivers/rtc/dev.c index abee1fc4705e..e104972a28fd 100644 --- a/drivers/rtc/dev.c +++ b/drivers/rtc/dev.c @@ -409,7 +409,10 @@ static long rtc_dev_ioctl(struct file *file, break; default: - err = -EINVAL; + if (rtc->ops->param_get) + err = rtc->ops->param_get(rtc->dev.parent, ¶m); + else + err = -EINVAL; } if (!err) @@ -436,7 +439,10 @@ static long rtc_dev_ioctl(struct file *file, return rtc_set_offset(rtc, param.svalue); default: - err = -EINVAL; + if (rtc->ops->param_set) + err = rtc->ops->param_set(rtc->dev.parent, ¶m); + else + err = -EINVAL; } break; diff --git a/include/linux/rtc.h b/include/linux/rtc.h index 354e0843ab17..47fd1c2d3a57 100644 --- a/include/linux/rtc.h +++ b/include/linux/rtc.h @@ -66,6 +66,8 @@ struct rtc_class_ops { int (*alarm_irq_enable)(struct device *, unsigned int enabled); int (*read_offset)(struct device *, long *offset); int (*set_offset)(struct device *, long offset); + int (*param_get)(struct device *, struct rtc_param *param); + int (*param_set)(struct device *, struct rtc_param *param); }; struct rtc_device; diff --git a/include/uapi/linux/rtc.h b/include/uapi/linux/rtc.h index 5debe82439c2..03e5b776e597 100644 --- a/include/uapi/linux/rtc.h +++ b/include/uapi/linux/rtc.h @@ -132,11 +132,18 @@ struct rtc_param { #define RTC_FEATURE_ALARM_RES_2S 3 #define RTC_FEATURE_UPDATE_INTERRUPT 4 #define RTC_FEATURE_CORRECTION 5 -#define RTC_FEATURE_CNT 6 +#define RTC_FEATURE_BACKUP_SWITCH_MODE 6 +#define RTC_FEATURE_CNT 7 /* parameter list */ #define RTC_PARAM_FEATURES 0 #define RTC_PARAM_CORRECTION 1 +#define RTC_PARAM_BACKUP_SWITCH_MODE 2 + +#define RTC_BSM_DISABLED 0 +#define RTC_BSM_DIRECT 1 +#define RTC_BSM_LEVEL 2 +#define RTC_BSM_STANDBY 3 #define RTC_MAX_FREQ 8192 -- cgit v1.2.3