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time: adjtimex: Validate the ADJ_FREQUENCY values

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Verify that the frequency value from userspace is valid and makes sense.

Unverified values can cause overflows later on.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
[jstultz: Fix up bug for negative values and drop redunent cap check]
Signed-off-by: John Stultz <john.stultz@linaro.org>
This commit is contained in:
Sasha Levin 2014-12-03 19:25:05 -05:00 committed by John Stultz
parent 6ada1fc0e1
commit 5e5aeb4367
1 changed files with 7 additions and 0 deletions
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7
kernel/time/ntp.c
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@ -633,6 +633,13 @@ int ntp_validate_timex(struct timex *txc)
if ((txc->modes & ADJ_SETOFFSET) && (!capable(CAP_SYS_TIME)))
return -EPERM;
if (txc->modes & ADJ_FREQUENCY) {
if (LONG_MIN / PPM_SCALE > txc->freq)
return -EINVAL;
if (LONG_MAX / PPM_SCALE < txc->freq)
return -EINVAL;
}
return 0;
}