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Subject[PATCH 3.4 089/176] time: adjtimex: Validate the ADJ_FREQUENCY values
Date
From: Sasha Levin <sasha.levin@oracle.com>

3.4.107-rc1 review patch. If anyone has any objections, please let me know.

------------------


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>
---
kernel/time/ntp.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/kernel/time/ntp.c b/kernel/time/ntp.c
index 8b70710..7666b24 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);
--
1.9.1


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