From: Mina Almasry <almasrymina@xxxxxxxxxx>
Subject: hugetlb_cgroup: fix illegal access to memory
This appears to be a mistake in commit faced7e0806cf ("mm: hugetlb
controller for cgroups v2"). Essentially that commit does a
hugetlb_cgroup_from_counter assuming that page_counter_try_charge has
initialized counter, but if page_counter_try_charge has failed then it
seems it does not initialize counter, so
hugetlb_cgroup_from_counter(counter) ends up pointing to random memory,
causing kasan to complain.
Solution, simply use h_cg, instead of
hugetlb_cgroup_from_counter(counter), since that is a reference to the
hugetlb_cgroup anyway. After this change kasan ceases to complain.
Link: http://lkml.kernel.org/r/20200313223920.124230-1-almasrymina@xxxxxxxxxx
Fixes: faced7e0806cf ("mm: hugetlb controller for cgroups v2")
Signed-off-by: Mina Almasry <almasrymina@xxxxxxxxxx>
Reported-by: syzbot+cac0c4e204952cf449b1@xxxxxxxxxxxxxxxxxxxxxxxxx
Acked-by: Giuseppe Scrivano <gscrivan@xxxxxxxxxx>
Acked-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb_cgroup.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/hugetlb_cgroup.c~hugetlb_cgroup-fix-illegal-access-to-memory
+++ a/mm/hugetlb_cgroup.c
@@ -240,8 +240,7 @@ again:
if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages,
&counter)) {
ret = -ENOMEM;
- hugetlb_event(hugetlb_cgroup_from_counter(counter, idx), idx,
- HUGETLB_MAX);
+ hugetlb_event(h_cg, idx, HUGETLB_MAX);
}
css_put(&h_cg->css);
done:
_
