From: Michal Hocko <mhocko@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com, Andrey Ryabinin <aryabinin@virtuozzo.com>, LKML <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>, Michal Hocko <mhocko@suse.com> Subject: [PATCH] memcg: fix per_node_info cleanup Date: Fri, 6 Apr 2018 12:09:06 +0200 [thread overview] Message-ID: <20180406100906.17790-1-mhocko@kernel.org> (raw) From: Michal Hocko <mhocko@suse.com> syzbot has triggered a NULL ptr dereference when allocation fault injection enforces a failure and alloc_mem_cgroup_per_node_info initializes memcg->nodeinfo only half way through. __mem_cgroup_free still tries to free all per-node data and dereferences pn->lruvec_stat_cpu unconditioanlly even if the specific per-node data hasn't been initialized. The bug is quite unlikely to hit because small allocations do not fail and we would need quite some numa nodes to make struct mem_cgroup_per_node large enough to cross the costly order. Reported-by: syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com Fixes: 00f3ca2c2d66 ("mm: memcontrol: per-lruvec stats infrastructure") Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Michal Hocko <mhocko@suse.com> --- Hi! Previously posted [1] based on the syzkaller report [2]. I haven't heard back from syzkaller but this seems like the right fix. Andrew could you add this to the pile? [1] http://lkml.kernel.org/r/20180403105048.GK5501@dhcp22.suse.cz [2] http://lkml.kernel.org/r/001a113fe4c0a623b10568bb75ea@google.com mm/memcontrol.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7667ea9daf4f..8c2ed1c2b72c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4340,6 +4340,9 @@ static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn = memcg->nodeinfo[node]; + if (!pn) + return; + free_percpu(pn->lruvec_stat_cpu); kfree(pn); } -- 2.16.3
WARNING: multiple messages have this Message-ID (diff)
From: Michal Hocko <mhocko@kernel.org> To: Andrew Morton <akpm@linux-foundation.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com, Andrey Ryabinin <aryabinin@virtuozzo.com>, LKML <linux-kernel@vger.kernel.org>, linux-mm@kvack.org, Michal Hocko <mhocko@suse.com> Subject: [PATCH] memcg: fix per_node_info cleanup Date: Fri, 6 Apr 2018 12:09:06 +0200 [thread overview] Message-ID: <20180406100906.17790-1-mhocko@kernel.org> (raw) From: Michal Hocko <mhocko@suse.com> syzbot has triggered a NULL ptr dereference when allocation fault injection enforces a failure and alloc_mem_cgroup_per_node_info initializes memcg->nodeinfo only half way through. __mem_cgroup_free still tries to free all per-node data and dereferences pn->lruvec_stat_cpu unconditioanlly even if the specific per-node data hasn't been initialized. The bug is quite unlikely to hit because small allocations do not fail and we would need quite some numa nodes to make struct mem_cgroup_per_node large enough to cross the costly order. Reported-by: syzbot+8a5de3cce7cdc70e9ebe@syzkaller.appspotmail.com Fixes: 00f3ca2c2d66 ("mm: memcontrol: per-lruvec stats infrastructure") Reviewed-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Michal Hocko <mhocko@suse.com> --- Hi! Previously posted [1] based on the syzkaller report [2]. I haven't heard back from syzkaller but this seems like the right fix. Andrew could you add this to the pile? [1] http://lkml.kernel.org/r/20180403105048.GK5501@dhcp22.suse.cz [2] http://lkml.kernel.org/r/001a113fe4c0a623b10568bb75ea@google.com mm/memcontrol.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7667ea9daf4f..8c2ed1c2b72c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4340,6 +4340,9 @@ static void free_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node) { struct mem_cgroup_per_node *pn = memcg->nodeinfo[node]; + if (!pn) + return; + free_percpu(pn->lruvec_stat_cpu); kfree(pn); } -- 2.16.3
next reply other threads:[~2018-04-06 10:09 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-06 10:09 Michal Hocko [this message] 2018-04-06 10:09 ` [PATCH] memcg: fix per_node_info cleanup Michal Hocko 2018-04-10 13:50 ` Sasha Levin 2018-04-10 14:01 ` Michal Hocko 2018-04-10 17:55 ` Sasha Levin 2018-04-10 20:37 ` Michal Hocko
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