time: Move ktime_t overflow checking into timespec_valid_strict

Andreas Bombe reported that the added ktime_t overflow checking added to
timespec_valid in commit 4e8b14526ca7 ("time: Improve sanity checking of
timekeeping inputs") was causing problems with X.org because it caused
timeouts larger then KTIME_T to be invalid.

Previously, these large timeouts would be clamped to KTIME_MAX and would
never expire, which is valid.

This patch splits the ktime_t overflow checking into a new
timespec_valid_strict function, and converts the timekeeping codes
internal checking to use this more strict function.

Reported-and-tested-by: Andreas Bombe <aeb@debian.org>
Cc: Zhouping Liu <zliu@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 12 insertions, 5 deletions

diff --git a/include/linux/time.h b/include/linux/time.h
index b0bbd8f0130d..b51e664c83e7 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -125,6 +125,13 @@ static inline bool timespec_valid(const struct timespec *ts)
         /* Can't have more nanoseconds then a second */
         if ((unsigned long)ts->tv_nsec >= NSEC_PER_SEC)
                 return false;
+        return true;
+}
+
+static inline bool timespec_valid_strict(const struct timespec *ts)
+{
+        if (!timespec_valid(ts))
+                return false;
         /* Disallow values that could overflow ktime_t */
         if ((unsigned long long)ts->tv_sec >= KTIME_SEC_MAX)
                 return false;
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index 0c1485e42be6..34e5eac81424 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -428,7 +428,7 @@ int do_settimeofday(const struct timespec *tv)
         struct timespec ts_delta, xt;
         unsigned long flags;
 
-        if (!timespec_valid(tv))
+        if (!timespec_valid_strict(tv))
                 return -EINVAL;
 
         write_seqlock_irqsave(&tk->lock, flags);
@@ -476,7 +476,7 @@ int timekeeping_inject_offset(struct timespec *ts)
 
         /* Make sure the proposed value is valid */
         tmp = timespec_add(tk_xtime(tk),  *ts);
-        if (!timespec_valid(&tmp)) {
+        if (!timespec_valid_strict(&tmp)) {
                 ret = -EINVAL;
                 goto error;
         }
@@ -659,7 +659,7 @@ void __init timekeeping_init(void)
         struct timespec now, boot, tmp;
 
         read_persistent_clock(&now);
-        if (!timespec_valid(&now)) {
+        if (!timespec_valid_strict(&now)) {
                 pr_warn("WARNING: Persistent clock returned invalid value!\n"
                         "         Check your CMOS/BIOS settings.\n");
                 now.tv_sec = 0;
@@ -667,7 +667,7 @@ void __init timekeeping_init(void)
         }
 
         read_boot_clock(&boot);
-        if (!timespec_valid(&boot)) {
+        if (!timespec_valid_strict(&boot)) {
                 pr_warn("WARNING: Boot clock returned invalid value!\n"
                         "         Check your CMOS/BIOS settings.\n");
                 boot.tv_sec = 0;
@@ -713,7 +713,7 @@ static struct timespec timekeeping_suspend_time;
 static void __timekeeping_inject_sleeptime(struct timekeeper *tk,
                                                         struct timespec *delta)
 {
-        if (!timespec_valid(delta)) {
+        if (!timespec_valid_strict(delta)) {
                 printk(KERN_WARNING "__timekeeping_inject_sleeptime: Invalid "
                                         "sleep delta value!\n");
                 return;