On 01/02/2015 11:51 AM, John Stultz wrote:
> From: Sasha Levin <sasha.le...@oracle.com>
>
> An unvalidated user input is multiplied by a constant, which can result in
> an undefined behaviour for large values. While this is validated later,
> we should avoid triggering undefined behaviour.
>
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@kernel.org>
> Cc: stable <sta...@vger.kernel.org>
> Signed-off-by: Sasha Levin <sasha.le...@oracle.com>
> Signed-off-by: John Stultz <john.stu...@linaro.org>
> ---
> include/linux/time.h | 13 +++++++++++++
> kernel/time/time.c | 4 ++++
> 2 files changed, 17 insertions(+)
>
> diff --git a/include/linux/time.h b/include/linux/time.h
> index 8c42cf8..7a10ec1 100644
> --- a/include/linux/time.h
> +++ b/include/linux/time.h
> @@ -99,6 +99,19 @@ static inline bool timespec_valid_strict(const struct
> timespec *ts)
> return true;
> }
>
> +static inline bool timeval_valid(const struct timeval *tv)
> +{
> + /* Dates before 1970 are bogus */
> + if (tv->tv_sec < 0)
> + return false;
> +
> + /* Can't have more miliseconds then a second */
Trivial nit: that should be "microseconds".
--Andy
> + if (tv->tv_usec < 0 || tv->tv_usec >= USEC_PER_SEC)
> + return false;
> +
> + return true;
> +}
> +
> extern struct timespec timespec_trunc(struct timespec t, unsigned gran);
>
> #define CURRENT_TIME (current_kernel_time())
> diff --git a/kernel/time/time.c b/kernel/time/time.c
> index a9ae20f..22d5d3b 100644
> --- a/kernel/time/time.c
> +++ b/kernel/time/time.c
> @@ -196,6 +196,10 @@ SYSCALL_DEFINE2(settimeofday, struct timeval __user *,
> tv,
> if (tv) {
> if (copy_from_user(&user_tv, tv, sizeof(*tv)))
> return -EFAULT;
> +
> + if (!timeval_valid(&user_tv))
> + return -EINVAL;
> +
> new_ts.tv_sec = user_tv.tv_sec;
> new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;
> }
>
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