lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Thu, 19 Jul 2018 17:38:46 -0700 From: John Stultz <john.stultz@...aro.org> To: lkml <linux-kernel@...r.kernel.org> Cc: Mukesh Ojha <mojha@...eaurora.org>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...nel.org>, Miroslav Lichvar <mlichvar@...hat.com>, Richard Cochran <richardcochran@...il.com>, Prarit Bhargava <prarit@...hat.com>, Stephen Boyd <sboyd@...nel.org>, John Stultz <john.stultz@...aro.org> Subject: [PATCH 4/5] time: Fix extra sleeptime injection when suspend fails From: Mukesh Ojha <mojha@...eaurora.org> Currently, there exists a corner case assuming when there is only one clocksource e.g RTC, and system failed to go to suspend mode. While resume rtc_resume() injects the sleeptime as timekeeping_rtc_skipresume() returned 'false' (default value of sleeptime_injected) due to which we can see mismatch in timestamps. This issue can also come in a system where more than one clocksource are present and very first suspend fails. Success case: ------------ {sleeptime_injected=false} rtc_suspend() => timekeeping_suspend() => timekeeping_resume() => (sleeptime injected) rtc_resume() Failure case: ------------ {failure in sleep path} {sleeptime_injected=false} rtc_suspend() => rtc_resume() {sleeptime injected again which was not required as the suspend failed} Fix this by handling the boolean logic properly. Cc: Thomas Gleixner <tglx@...utronix.de> Cc: Ingo Molnar <mingo@...nel.org> Cc: Miroslav Lichvar <mlichvar@...hat.com> Cc: Richard Cochran <richardcochran@...il.com> Cc: Prarit Bhargava <prarit@...hat.com> Cc: Stephen Boyd <sboyd@...nel.org> Originally-by: Thomas Gleixner <tglx@...utronix.de> Signed-off-by: Mukesh Ojha <mojha@...eaurora.org> Signed-off-by: John Stultz <john.stultz@...aro.org> --- kernel/time/timekeeping.c | 32 +++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 7033ac1..19414b1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1519,8 +1519,20 @@ void __weak read_boot_clock64(struct timespec64 *ts) ts->tv_nsec = 0; } -/* Flag for if timekeeping_resume() has injected sleeptime */ -static bool sleeptime_injected; +/* + * Flag reflecting whether timekeeping_resume() has injected sleeptime. + * + * The flag starts of false and is only set when a suspend reaches + * timekeeping_suspend(), timekeeping_resume() sets it to false when the + * timekeeper clocksource is not stopping across suspend and has been + * used to update sleep time. If the timekeeper clocksource has stopped + * then the flag stays true and is used by the RTC resume code to decide + * whether sleeptime must be injected and if so the flag gets false then. + * + * If a suspend fails before reaching timekeeping_resume() then the flag + * stays false and prevents erroneous sleeptime injection. + */ +static bool suspend_timing_needed; /* Flag for if there is a persistent clock on this platform */ static bool persistent_clock_exists; @@ -1619,7 +1631,7 @@ static void __timekeeping_inject_sleeptime(struct timekeeper *tk, */ bool timekeeping_rtc_skipresume(void) { - return sleeptime_injected; + return !suspend_timing_needed; } /** @@ -1655,6 +1667,8 @@ void timekeeping_inject_sleeptime64(const struct timespec64 *delta) raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq); + suspend_timing_needed = false; + timekeeping_forward_now(tk); __timekeeping_inject_sleeptime(tk, delta); @@ -1679,8 +1693,8 @@ void timekeeping_resume(void) unsigned long flags; struct timespec64 ts_new, ts_delta; u64 cycle_now; + bool inject_sleeptime = false; - sleeptime_injected = false; read_persistent_clock64(&ts_new); clockevents_resume(); @@ -1710,14 +1724,16 @@ void timekeeping_resume(void) tk->tkr_mono.mask); nsec = mul_u64_u32_shr(cyc_delta, clock->mult, clock->shift); ts_delta = ns_to_timespec64(nsec); - sleeptime_injected = true; + inject_sleeptime = true; } else if (timespec64_compare(&ts_new, &timekeeping_suspend_time) > 0) { ts_delta = timespec64_sub(ts_new, timekeeping_suspend_time); - sleeptime_injected = true; + inject_sleeptime = true; } - if (sleeptime_injected) + if (inject_sleeptime) { + suspend_timing_needed = false; __timekeeping_inject_sleeptime(tk, &ts_delta); + } /* Re-base the last cycle value */ tk->tkr_mono.cycle_last = cycle_now; @@ -1752,6 +1768,8 @@ int timekeeping_suspend(void) if (timekeeping_suspend_time.tv_sec || timekeeping_suspend_time.tv_nsec) persistent_clock_exists = true; + suspend_timing_needed = true; + raw_spin_lock_irqsave(&timekeeper_lock, flags); write_seqcount_begin(&tk_core.seq); timekeeping_forward_now(tk); -- 2.7.4
Powered by blists - more mailing lists