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authorJing Xia <jing.xia.mail@gmail.com>2018-07-20 17:53:48 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-07-21 12:50:46 -0700
commit9f15bde671355c351cf20d9f879004b234353100 (patch)
tree4b898132d09c087cdc30f91b941dcaf4e22f9160
parentmm/huge_memory.c: fix data loss when splitting a file pmd (diff)
downloadlinux-dev-9f15bde671355c351cf20d9f879004b234353100.tar.xz
linux-dev-9f15bde671355c351cf20d9f879004b234353100.zip
mm: memcg: fix use after free in mem_cgroup_iter()
It was reported that a kernel crash happened in mem_cgroup_iter(), which can be triggered if the legacy cgroup-v1 non-hierarchical mode is used. Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b8f ...... Call trace: mem_cgroup_iter+0x2e0/0x6d4 shrink_zone+0x8c/0x324 balance_pgdat+0x450/0x640 kswapd+0x130/0x4b8 kthread+0xe8/0xfc ret_from_fork+0x10/0x20 mem_cgroup_iter(): ...... if (css_tryget(css)) <-- crash here break; ...... The crashing reason is that mem_cgroup_iter() uses the memcg object whose pointer is stored in iter->position, which has been freed before and filled with POISON_FREE(0x6b). And the root cause of the use-after-free issue is that invalidate_reclaim_iterators() fails to reset the value of iter->position to NULL when the css of the memcg is released in non- hierarchical mode. Link: http://lkml.kernel.org/r/1531994807-25639-1-git-send-email-jing.xia@unisoc.com Fixes: 6df38689e0e9 ("mm: memcontrol: fix possible memcg leak due to interrupted reclaim") Signed-off-by: Jing Xia <jing.xia.mail@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: <chunyan.zhang@unisoc.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/memcontrol.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e6f0d5ef320a..8c0280b3143e 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -850,7 +850,7 @@ static void invalidate_reclaim_iterators(struct mem_cgroup *dead_memcg)
int nid;
int i;
- while ((memcg = parent_mem_cgroup(memcg))) {
+ for (; memcg; memcg = parent_mem_cgroup(memcg)) {
for_each_node(nid) {
mz = mem_cgroup_nodeinfo(memcg, nid);
for (i = 0; i <= DEF_PRIORITY; i++) {