[ 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 1ef2fb4bbd6bd..0e70bfeded7fd 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8361,6 +8361,8 @@ 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)); }