From bae0361d4d499c272f4a11bf1c41b01c2eed7c3e Mon Sep 17 00:00:00 2001
From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Date: Wed, 27 Feb 2019 11:10:18 +0300
Subject: [PATCH] sched/core: Handle overflow in cpu_shares_write_u64
References: git fixes
Patch-mainline: v5.2-rc1
Git-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: Mel Gorman <mgorman@suse.de>
---
kernel/sched/core.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 4da0c86d421d..e7382e8d094d 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7037,6 +7037,8 @@ 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));
}