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From 0155adc8a0e61c0b1b7dc8febcba049b0d84bb31 Mon Sep 17 00:00:00 2001
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From: Brent Cook <busterb@gmail.com>
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Date: Sun, 22 Mar 2015 16:18:20 -0500
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Subject: [PATCH 11/11] Account for integer overflows with a 32-bit time_t
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If the current time is set past Feb. 2036, adding the NTP epoch offset
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overflows the time_t. While all systems in 2036 should have been running
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with a larger time_t for some time, today an invalid system clock cannot
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be reset with the overflow.
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Thanks to @Romua1d on github for point it out.
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---
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src/usr.sbin/ntpd/client.c | 6 +++++-
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src/usr.sbin/ntpd/util.c | 12 ++++++++++--
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2 files changed, 15 insertions(+), 3 deletions(-)
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diff --git a/src/usr.sbin/ntpd/client.c b/src/usr.sbin/ntpd/client.c
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index d47869b..70879c0 100644
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--- a/src/usr.sbin/ntpd/client.c
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+++ b/src/usr.sbin/ntpd/client.c
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@@ -269,7 +269,11 @@ client_dispatch(struct ntp_peer *p, u_int8_t settime)
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if (cmsg->cmsg_level == SOL_SOCKET &&
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cmsg->cmsg_type == SCM_TIMESTAMP) {
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memcpy(&tv, CMSG_DATA(cmsg), sizeof(tv));
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- T4 += tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec;
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+ /*
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+ * account for overflow that occurs on OSes that still
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+ * have a 32-bit time_t.
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+ */
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+ T4 += (uint64_t)tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec;
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break;
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}
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}
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diff --git a/src/usr.sbin/ntpd/util.c b/src/usr.sbin/ntpd/util.c
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index 0867ed7..e9f6d50 100644
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--- a/src/usr.sbin/ntpd/util.c
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+++ b/src/usr.sbin/ntpd/util.c
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@@ -45,13 +45,21 @@ gettime(void)
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if (gettimeofday(&tv, NULL) == -1)
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fatal("gettimeofday");
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- return (tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec);
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+ /*
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+ * account for overflow that occurs on OSes that still
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+ * have a 32-bit time_t.
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+ */
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+ return ((uint64_t)tv.tv_sec + JAN_1970 + 1.0e-6 * tv.tv_usec);
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}
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double
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gettime_from_timeval(struct timeval *tv)
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{
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- return (tv->tv_sec + JAN_1970 + 1.0e-6 * tv->tv_usec);
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+ /*
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+ * account for overflow that occurs on OSes that still
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+ * have a 32-bit time_t.
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+ */
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+ return ((uint64_t)tv->tv_sec + JAN_1970 + 1.0e-6 * tv->tv_usec);
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}
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time_t
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--
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1.9.1
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