From: Sasha Levin <sasha.levin@oracle.com>
Date: Thu, 4 Dec 2014 00:25:05 +0000 (-0500)
Subject: time: adjtimex: Validate the ADJ_FREQUENCY values
X-Git-Tag: v3.4.107~89
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f6d9b62622ce5dbb870160cb3da5f8bfc87adee;p=thirdparty%2Fkernel%2Fstable.git

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>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 8b707100286b8..7666b24ca9ab0 100644
--- a/kernel/time/ntp.c
+++ b/kernel/time/ntp.c
@@ -660,6 +660,13 @@ int do_adjtimex(struct timex *txc)
 			return result;
 	}
 
+	if (txc->modes & ADJ_FREQUENCY) {
+		if (LONG_MIN / PPM_SCALE > txc->freq)
+			return -EINVAL;
+		if (LONG_MAX / PPM_SCALE < txc->freq)
+			return -EINVAL;
+	}
+
 	getnstimeofday(&ts);
 
 	spin_lock_irq(&ntp_lock);