This is a note to let you know that I've just added the patch titled
rtc: Check return value from mc146818_get_time()
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
rtc-check-return-value-from-mc146818_get_time.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 7a3b77a291c1fb84974f59d34a2d5cf044f52d8f
Author: Mateusz Jończyk <mat.jonczyk@xxxxx>
Date: Fri Dec 10 21:01:25 2021 +0100
rtc: Check return value from mc146818_get_time()
[ Upstream commit 0dd8d6cb9eddfe637bcd821bbfd40ebd5a0737b9 ]
There are 4 users of mc146818_get_time() and none of them was checking
the return value from this function. Change this.
Print the appropriate warnings in callers of mc146818_get_time() instead
of in the function mc146818_get_time() itself, in order not to add
strings to rtc-mc146818-lib.c, which is kind of a library.
The callers of alpha_rtc_read_time() and cmos_read_time() may use the
contents of (struct rtc_time *) even when the functions return a failure
code. Therefore, set the contents of (struct rtc_time *) to 0x00,
which looks more sensible then 0xff and aligns with the (possibly
stale?) comment in cmos_read_time:
/*
* If pm_trace abused the RTC for storage, set the timespec to 0,
* which tells the caller that this RTC value is unusable.
*/
For consistency, do this in mc146818_get_time().
Note: hpet_rtc_interrupt() may call mc146818_get_time() many times a
second. It is very unlikely, though, that the RTC suddenly stops
working and mc146818_get_time() would consistently fail.
Only compile-tested on alpha.
Signed-off-by: Mateusz Jończyk <mat.jonczyk@xxxxx>
Cc: Richard Henderson <rth@xxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Cc: linux-alpha@xxxxxxxxxxxxxxx
Cc: x86@xxxxxxxxxx
Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/20211210200131.153887-4-mat.jonczyk@xxxxx
Stable-dep-of: cd17420ebea5 ("rtc: cmos: avoid UIP when writing alarm time")
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/alpha/kernel/rtc.c b/arch/alpha/kernel/rtc.c
index 1b1d5963ac55..48ffbfbd0624 100644
--- a/arch/alpha/kernel/rtc.c
+++ b/arch/alpha/kernel/rtc.c
@@ -80,7 +80,12 @@ init_rtc_epoch(void)
static int
alpha_rtc_read_time(struct device *dev, struct rtc_time *tm)
{
- mc146818_get_time(tm);
+ int ret = mc146818_get_time(tm);
+
+ if (ret < 0) {
+ dev_err_ratelimited(dev, "unable to read current time\n");
+ return ret;
+ }
/* Adjust for non-default epochs. It's easier to depend on the
generic __get_rtc_time and adjust the epoch here than create
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 4ab7a9757e52..574df24a8e5a 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -1325,8 +1325,12 @@ irqreturn_t hpet_rtc_interrupt(int irq, void *dev_id)
hpet_rtc_timer_reinit();
memset(&curr_time, 0, sizeof(struct rtc_time));
- if (hpet_rtc_flags & (RTC_UIE | RTC_AIE))
- mc146818_get_time(&curr_time);
+ if (hpet_rtc_flags & (RTC_UIE | RTC_AIE)) {
+ if (unlikely(mc146818_get_time(&curr_time) < 0)) {
+ pr_err_ratelimited("unable to read current time from RTC\n");
+ return IRQ_HANDLED;
+ }
+ }
if (hpet_rtc_flags & RTC_UIE &&
curr_time.tm_sec != hpet_prev_update_sec) {
diff --git a/drivers/base/power/trace.c b/drivers/base/power/trace.c
index 94665037f4a3..72b7a92337b1 100644
--- a/drivers/base/power/trace.c
+++ b/drivers/base/power/trace.c
@@ -120,7 +120,11 @@ static unsigned int read_magic_time(void)
struct rtc_time time;
unsigned int val;
- mc146818_get_time(&time);
+ if (mc146818_get_time(&time) < 0) {
+ pr_err("Unable to read current time from RTC\n");
+ return 0;
+ }
+
pr_info("RTC time: %ptRt, date: %ptRd\n", &time, &time);
val = time.tm_year; /* 100 years */
if (val > 100)
diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
index ed4f512eabf0..f8358bb2ae31 100644
--- a/drivers/rtc/rtc-cmos.c
+++ b/drivers/rtc/rtc-cmos.c
@@ -222,6 +222,8 @@ static inline void cmos_write_bank2(unsigned char val, unsigned char addr)
static int cmos_read_time(struct device *dev, struct rtc_time *t)
{
+ int ret;
+
/*
* If pm_trace abused the RTC for storage, set the timespec to 0,
* which tells the caller that this RTC value is unusable.
@@ -229,7 +231,12 @@ static int cmos_read_time(struct device *dev, struct rtc_time *t)
if (!pm_trace_rtc_valid())
return -EIO;
- mc146818_get_time(t);
+ ret = mc146818_get_time(t);
+ if (ret < 0) {
+ dev_err_ratelimited(dev, "unable to read current time\n");
+ return ret;
+ }
+
return 0;
}
diff --git a/drivers/rtc/rtc-mc146818-lib.c b/drivers/rtc/rtc-mc146818-lib.c
index 6262f0680f13..3ae5c690f22b 100644
--- a/drivers/rtc/rtc-mc146818-lib.c
+++ b/drivers/rtc/rtc-mc146818-lib.c
@@ -24,7 +24,7 @@ unsigned int mc146818_get_time(struct rtc_time *time)
/* Ensure that the RTC is accessible. Bit 6 must be 0! */
if (WARN_ON_ONCE((CMOS_READ(RTC_VALID) & 0x40) != 0)) {
spin_unlock_irqrestore(&rtc_lock, flags);
- memset(time, 0xff, sizeof(*time));
+ memset(time, 0, sizeof(*time));
return -EIO;
}
