lkml.org 
[lkml]   [2019]   [May]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.19 138/276] sched/core: Handle overflow in cpu_shares_write_u64
    Date
    [ Upstream commit 5b61d50ab4ef590f5e1d4df15cd2cea5f5715308 ]

    Bit shift in scale_load() could overflow shares. This patch saturates
    it to MAX_SHARES like following sched_group_set_shares().

    Example:

    # echo 9223372036854776832 > cpu.shares
    # cat cpu.shares

    Before patch: 1024
    After pattch: 262144

    Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
    Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Link: http://lkml.kernel.org/r/155125501891.293431.3345233332801109696.stgit@buzz
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    kernel/sched/core.c | 2 ++
    1 file changed, 2 insertions(+)

    diff --git a/kernel/sched/core.c b/kernel/sched/core.c
    index bd5ae34c20c0b..6138754e5030f 100644
    --- a/kernel/sched/core.c
    +++ b/kernel/sched/core.c
    @@ -6491,6 +6491,8 @@ static void cpu_cgroup_attach(struct cgroup_taskset *tset)
    static int cpu_shares_write_u64(struct cgroup_subsys_state *css,
    struct cftype *cftype, u64 shareval)
    {
    + if (shareval > scale_load_down(ULONG_MAX))
    + shareval = MAX_SHARES;
    return sched_group_set_shares(css_tg(css), scale_load(shareval));
    }

    --
    2.20.1


    \
     
     \ /
      Last update: 2019-05-30 06:10    [W:4.166 / U:0.256 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site