From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: [patch 3/5] hugetlb_cgroup: fix illegal access to memory Date: Sat, 28 Mar 2020 19:17:22 -0700 Message-ID: <20200329021722.W_psAYHe4%akpm@linux-foundation.org> References: <20200328191456.4fc0b9ca86780f26c122399e@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:38836 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726315AbgC2CRX (ORCPT ); Sat, 28 Mar 2020 22:17:23 -0400 In-Reply-To: <20200328191456.4fc0b9ca86780f26c122399e@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: akpm@linux-foundation.org, almasrymina@google.com, gscrivan@redhat.com, linux-mm@kvack.org, mike.kravetz@oracle.com, mm-commits@vger.kernel.org, rientjes@google.com, tj@kernel.org, torvalds@linux-foundation.org From: Mina Almasry 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@google.com Fixes: faced7e0806cf ("mm: hugetlb controller for cgroups v2") Signed-off-by: Mina Almasry Reported-by: syzbot+cac0c4e204952cf449b1@syzkaller.appspotmail.com Acked-by: Giuseppe Scrivano Acked-by: Tejun Heo Cc: Mike Kravetz Cc: David Rientjes Signed-off-by: Andrew Morton --- 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: _