time: Move ktime_t overflow checking into timespec_valid_strict

This is a -stable backport of cee58483cf56e0ba355fdd97ff5e8925329aa936

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>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/include/linux/time.h b/include/linux/time.h
index 146b6f3c23b9410a46a6fcd5c9fa189f1efc44bb..bc93987d05a0dd409fd38cb80fbb25c78a8d11b4 100644 (file)
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -109,6 +109,13 @@ 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 b451c9376f446166eb0aad87c692132ce4a107eb..3d35af308f6bb4ba7c461ee97429525fc1d8cbc6 100644 (file)
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -354,7 +354,7 @@ int do_settimeofday(struct timespec *tv)
        struct timespec ts_delta;
        unsigned long flags;
 
-       if (!timespec_valid(tv))
+       if (!timespec_valid_strict(tv))
                return -EINVAL;
 
        write_seqlock_irqsave(&xtime_lock, flags);
@@ -570,7 +570,7 @@ void __init timekeeping_init(void)
        struct timespec now, boot;
 
        read_persistent_clock(&now);
-       if (!timespec_valid(&now)) {
+       if (!timespec_valid_strict(&now)) {
                printk("WARNING: Persistent clock returned invalid value!\n"
                        "         Check your CMOS/BIOS settings.\n");
                now.tv_sec = 0;
@@ -578,7 +578,7 @@ void __init timekeeping_init(void)
        }
 
        read_boot_clock(&boot);
-       if (!timespec_valid(&boot)) {
+       if (!timespec_valid_strict(&boot)) {
                printk("WARNING: Boot clock returned invalid value!\n"
                        "         Check your CMOS/BIOS settings.\n");
                boot.tv_sec = 0;