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[ Upstream commit5a8c02a6bf] Networking drivers implementing PTP clocks and kernel socket code handling hardware timestamps use the 64-bit signed ktime_t type counting nanoseconds. When a PTP clock reaches the maximum value in year 2262, the timestamps returned to applications will overflow into year 1667. The same thing happens when injecting a large offset with clock_adjtime(ADJ_SETOFFSET). The commit7a8e61f847("timekeeping: Force upper bound for setting CLOCK_REALTIME") limited the maximum accepted value setting the system clock to 30 years before the maximum representable value (i.e. year 2232) to avoid the overflow, assuming the system will not run for more than 30 years. Enforce the same limit for PTP clocks. Don't allow negative values and values closer than 30 years to the maximum value. Drivers may implement an even lower limit if the hardware registers cannot represent the whole interval between years 1970 and 2262 in the required resolution. Signed-off-by: Miroslav Lichvar <mlichvar@redhat.com> Cc: Richard Cochran <richardcochran@gmail.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: John Stultz <jstultz@google.com> Cc: Arnd Bergmann <arnd@arndb.de> Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev> Link: https://patch.msgid.link/20250828103300.1387025-1-mlichvar@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org>