time: adjtimex: Validate the ADJ_FREQUENCY values
authorSasha Levin <sasha.levin@oracle.com>
Thu, 4 Dec 2014 00:25:05 +0000 (19:25 -0500)
committerJohn Stultz <john.stultz@linaro.org>
Wed, 7 Jan 2015 17:50:32 +0000 (09:50 -0800)
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>
kernel/time/ntp.c

index 87a346fd6d61ff1c5c1045c9db063ee3247d2361..28bf91c60a0b412d1c97911659c30d735ba40d78 100644 (file)
@@ -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;
 }