Commit-ID: 6ea565a9be32a3c8d1092017686f183b6d8c4514 Gitweb: http://git.kernel.org/tip/6ea565a9be32a3c8d1092017686f183b6d8c4514 Author: John Stultz <john.stultz@xxxxxxxxxx> AuthorDate: Tue, 21 Aug 2012 20:30:48 -0400 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 22 Aug 2012 10:42:13 +0200 time: Avoid potential shift overflow with large shift values Andreas Schwab noticed that the 1 << tk->shift could overflow if the shift value was greater than 30, since 1 would be a 32bit long on 32bit architectures. This issue was introduced by 1e75fa8be (time: Condense timekeeper.xtime into xtime_sec) Use 1ULL instead to ensure we don't overflow on the shift. Reported-by: Andreas Schwab <schwab@xxxxxxxxxxxxxx> Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> Cc: Prarit Bhargava <prarit@xxxxxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxxxxx> Link: http://lkml.kernel.org/r/1345595449-34965-4-git-send-email-john.stultz@xxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- kernel/time/timekeeping.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 1dbf80e..a5a9389 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1184,9 +1184,9 @@ static void update_wall_time(void) * the vsyscall implementations are converted to use xtime_nsec * (shifted nanoseconds), this can be killed. */ - remainder = tk->xtime_nsec & ((1 << tk->shift) - 1); + remainder = tk->xtime_nsec & ((1ULL << tk->shift) - 1); tk->xtime_nsec -= remainder; - tk->xtime_nsec += 1 << tk->shift; + tk->xtime_nsec += 1ULL << tk->shift; tk->ntp_error += remainder << tk->ntp_error_shift; /* -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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