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authorWang YanQing <udknight@gmail.com>2015-06-23 18:38:54 +0800
committerJohn Stultz <john.stultz@linaro.org>2015-08-17 11:24:54 -0700
commite1d7ba8735551ed79c7a0463a042353574b96da3 (patch)
treef15a9ef6516d689f6edaf062079000e32e8a7c77 /kernel/time
parentde4a95faf173be1e798c37ca486dfcb234a0941b (diff)
time: Always make sure wall_to_monotonic isn't positive
Two issues were found on an IMX6 development board without an enabled RTC device(resulting in the boot time and monotonic time being initialized to 0). Issue 1:exportfs -a generate: "exportfs: /opt/nfs/arm does not support NFS export" Issue 2:cat /proc/stat: "btime 4294967236" The same issues can be reproduced on x86 after running the following code: int main(void) { struct timeval val; int ret; val.tv_sec = 0; val.tv_usec = 0; ret = settimeofday(&val, NULL); return 0; } Two issues are different symptoms of same problem: The reason is a positive wall_to_monotonic pushes boot time back to the time before Epoch, and getboottime will return negative value. In symptom 1: negative boot time cause get_expiry() to overflow time_t when input expire time is 2147483647, then cache_flush() always clears entries just added in ip_map_parse. In symptom 2: show_stat() uses "unsigned long" to print negative btime value returned by getboottime. This patch fix the problem by prohibiting time from being set to a value which would cause a negative boot time. As a result one can't set the CLOCK_REALTIME time prior to (1970 + system uptime). Cc: Prarit Bhargava <prarit@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Wang YanQing <udknight@gmail.com> [jstultz: reworded commit message] Signed-off-by: John Stultz <john.stultz@linaro.org>
Diffstat (limited to 'kernel/time')
-rw-r--r--kernel/time/timekeeping.c13
1 files changed, 10 insertions, 3 deletions
diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c
index bca3667a2de1..4cdb771913c8 100644
--- a/kernel/time/timekeeping.c
+++ b/kernel/time/timekeeping.c
@@ -911,6 +911,7 @@ int do_settimeofday64(const struct timespec64 *ts)
struct timekeeper *tk = &tk_core.timekeeper;
struct timespec64 ts_delta, xt;
unsigned long flags;
+ int ret = 0;
if (!timespec64_valid_strict(ts))
return -EINVAL;
@@ -924,10 +925,15 @@ int do_settimeofday64(const struct timespec64 *ts)
ts_delta.tv_sec = ts->tv_sec - xt.tv_sec;
ts_delta.tv_nsec = ts->tv_nsec - xt.tv_nsec;
+ if (timespec64_compare(&tk->wall_to_monotonic, &ts_delta) > 0) {
+ ret = -EINVAL;
+ goto out;
+ }
+
tk_set_wall_to_mono(tk, timespec64_sub(tk->wall_to_monotonic, ts_delta));
tk_set_xtime(tk, ts);
-
+out:
timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET);
write_seqcount_end(&tk_core.seq);
@@ -936,7 +942,7 @@ int do_settimeofday64(const struct timespec64 *ts)
/* signal hrtimers about time change */
clock_was_set();
- return 0;
+ return ret;
}
EXPORT_SYMBOL(do_settimeofday64);
@@ -965,7 +971,8 @@ int timekeeping_inject_offset(struct timespec *ts)
/* Make sure the proposed value is valid */
tmp = timespec64_add(tk_xtime(tk), ts64);
- if (!timespec64_valid_strict(&tmp)) {
+ if (timespec64_compare(&tk->wall_to_monotonic, &ts64) > 0 ||
+ !timespec64_valid_strict(&tmp)) {
ret = -EINVAL;
goto error;
}