time: adjtimex: Validate the ADJ_FREQUENCY values

commit 5e5aeb4367b450a28f447f6d5ab57d8f2ab16a5f upstream.

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>
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index af8d1d4f3d55156eaae7936b1a34d8cd7141248f..28db9bedc857103bc9b35c69602a82598e8828b0 100644 (file)
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -631,6 +631,13 @@ 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;
 }