Commit e87f89e9 authored Feb 28, 2024 by GONG, Ruiqi

Revert "memcg: fix a UAF problem in drain_all_stock()"

hulk inclusion
category: bugfix
bugzilla: 189183, https://gitee.com/openeuler/kernel/issues/I7Z1ZU


CVE: NA

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

This reverts commit 616e7082 ("memcg: fix a UAF problem in
drain_all_stock()"), which was produced based on in-house 3.10 and later
was found to be not suitable for in-house 4.18/4.19, as both of them use
async version of drain_all_stock() whose actual draining could be
delayed, and some of them even removed drain_all_stock() from memcg's
offline process. In these cases the commit doesn't fix the original
problem.

Fixes: 616e7082 ("memcg: fix a UAF problem in drain_all_stock()")
Signed-off-by: GONG, Ruiqi <gongruiqi1@huawei.com>

parent f4144fbf

mm/memcontrol.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -2232,7 +2232,8 @@ static void drain_all_stock(struct mem_cgroup *root_memcg)

		rcu_read_lock();
		memcg = stock->cached;
		if (memcg && mem_cgroup_is_descendant(memcg, root_memcg))
		if (memcg && stock->nr_pages &&
		mem_cgroup_is_descendant(memcg, root_memcg))
		flush = true;
		rcu_read_unlock();