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    Subject[PATCH 4.4 153/342] cputime: Prevent 32bit overflow in time[val|spec]_to_cputime()
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

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

    From: zengtao <prime.zeng@huawei.com>

    commit 0f26922fe5dc5724b1adbbd54b21bad03590b4f3 upstream.

    The datatype __kernel_time_t is u32 on 32bit platform, so its subject to
    overflows in the timeval/timespec to cputime conversion.

    Currently the following functions are affected:
    1. setitimer()
    2. timer_create/timer_settime()
    3. sys_clock_nanosleep

    This can happen on MIPS32 and ARM32 with "Full dynticks CPU time accounting"
    enabled, which is required for CONFIG_NO_HZ_FULL.

    Enforce u64 conversion to prevent the overflow.

    Fixes: 31c1fc818715 ("ARM: Kconfig: allow full nohz CPU accounting")
    Signed-off-by: zengtao <prime.zeng@huawei.com>
    Reviewed-by: Arnd Bergmann <arnd@arndb.de>
    Cc: <fweisbec@gmail.com>
    Link: http://lkml.kernel.org/r/1454384314-154784-1-git-send-email-prime.zeng@huawei.com
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    include/asm-generic/cputime_nsecs.h | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    --- a/include/asm-generic/cputime_nsecs.h
    +++ b/include/asm-generic/cputime_nsecs.h
    @@ -75,7 +75,7 @@ typedef u64 __nocast cputime64_t;
    */
    static inline cputime_t timespec_to_cputime(const struct timespec *val)
    {
    - u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
    + u64 ret = (u64)val->tv_sec * NSEC_PER_SEC + val->tv_nsec;
    return (__force cputime_t) ret;
    }
    static inline void cputime_to_timespec(const cputime_t ct, struct timespec *val)
    @@ -91,7 +91,8 @@ static inline void cputime_to_timespec(c
    */
    static inline cputime_t timeval_to_cputime(const struct timeval *val)
    {
    - u64 ret = val->tv_sec * NSEC_PER_SEC + val->tv_usec * NSEC_PER_USEC;
    + u64 ret = (u64)val->tv_sec * NSEC_PER_SEC +
    + val->tv_usec * NSEC_PER_USEC;
    return (__force cputime_t) ret;
    }
    static inline void cputime_to_timeval(const cputime_t ct, struct timeval *val)
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