[PATCH 3.13.y-ckt 065/103] time: adjtimex: Validate the ADJ_FREQUENCY values

Kamal Mostafa
2015-02-19T00:47:46Z

From: Sasha Levin <sasha.levin@oracle.com>

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: Kamal Mostafa <kamal@canonical.com>
---
kernel/time/ntp.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index af8d1d4..28db9be 100644
--- 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;
}

--
1.9.1