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    Subject[PATCH 3.4 088/176] time: settimeofday: Validate the values of tv from user
    Date
    From: Sasha Levin <sasha.levin@oracle.com>

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

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


    commit 6ada1fc0e1c4775de0e043e1bd3ae9d065491aa5 upstream.

    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 <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
    [jstultz: include trivial milisecond->microsecond correction noticed
    by Andy]
    Signed-off-by: John Stultz <john.stultz@linaro.org>
    [lizf: Backported to 3.4: adjust filename]
    Signed-off-by: Zefan Li <lizefan@huawei.com>
    ---
    include/linux/time.h | 13 +++++++++++++
    kernel/time.c | 4 ++++
    2 files changed, 17 insertions(+)

    diff --git a/include/linux/time.h b/include/linux/time.h
    index 03dce74..bf1bb61 100644
    --- a/include/linux/time.h
    +++ b/include/linux/time.h
    @@ -189,6 +189,19 @@ extern void getboottime(struct timespec *ts);
    extern void monotonic_to_bootbased(struct timespec *ts);
    extern void get_monotonic_boottime(struct timespec *ts);

    +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 microseconds then a second */
    + 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);
    extern int timekeeping_valid_for_hres(void);
    extern u64 timekeeping_max_deferment(void);
    diff --git a/kernel/time.c b/kernel/time.c
    index a095290..0864d70 100644
    --- a/kernel/time.c
    +++ b/kernel/time.c
    @@ -186,6 +186,10 @@ 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;
    }
    --
    1.9.1


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