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sched/core: Handle overflow in cpu_shares_write_u64

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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>
This commit is contained in:
Konstantin Khlebnikov 2019-02-27 11:10:18 +03:00 committed by Ingo Molnar
parent 1a010e29cf
commit 5b61d50ab4
1 changed files with 2 additions and 0 deletions
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2
kernel/sched/core.c
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@ -6507,6 +6507,8 @@ 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));
}