From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org,
syzbot+7fbbfa368521945f0e3d@syzkaller.appspotmail.com,
Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
Michal Hocko <mhocko@suse.com>,
David Rientjes <rientjes@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: [PATCH 4.14 40/46] mm, oom: fix use-after-free in oom_kill_process
Date: Mon, 4 Feb 2019 11:37:11 +0100 [thread overview]
Message-ID: <20190204103615.656474440@linuxfoundation.org> (raw)
In-Reply-To: <20190204103608.651205056@linuxfoundation.org>
4.14-stable review patch. If anyone has any objections, please let me know.
------------------
From: Shakeel Butt <shakeelb@google.com>
commit cefc7ef3c87d02fc9307835868ff721ea12cc597 upstream.
Syzbot instance running on upstream kernel found a use-after-free bug in
oom_kill_process. On further inspection it seems like the process
selected to be oom-killed has exited even before reaching
read_lock(&tasklist_lock) in oom_kill_process(). More specifically the
tsk->usage is 1 which is due to get_task_struct() in oom_evaluate_task()
and the put_task_struct within for_each_thread() frees the tsk and
for_each_thread() tries to access the tsk. The easiest fix is to do
get/put across the for_each_thread() on the selected task.
Now the next question is should we continue with the oom-kill as the
previously selected task has exited? However before adding more
complexity and heuristics, let's answer why we even look at the children
of oom-kill selected task? The select_bad_process() has already selected
the worst process in the system/memcg. Due to race, the selected
process might not be the worst at the kill time but does that matter?
The userspace can use the oom_score_adj interface to prefer children to
be killed before the parent. I looked at the history but it seems like
this is there before git history.
Link: http://lkml.kernel.org/r/20190121215850.221745-1-shakeelb@google.com
Reported-by: syzbot+7fbbfa368521945f0e3d@syzkaller.appspotmail.com
Fixes: 6b0c81b3be11 ("mm, oom: reduce dependency on tasklist_lock")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Roman Gushchin <guro@fb.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/oom_kill.c | 8 ++++++++
1 file changed, 8 insertions(+)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -870,6 +870,13 @@ static void oom_kill_process(struct oom_
* still freeing memory.
*/
read_lock(&tasklist_lock);
+
+ /*
+ * The task 'p' might have already exited before reaching here. The
+ * put_task_struct() will free task_struct 'p' while the loop still try
+ * to access the field of 'p', so, get an extra reference.
+ */
+ get_task_struct(p);
for_each_thread(p, t) {
list_for_each_entry(child, &t->children, sibling) {
unsigned int child_points;
@@ -889,6 +896,7 @@ static void oom_kill_process(struct oom_
}
}
}
+ put_task_struct(p);
read_unlock(&tasklist_lock);
p = find_lock_task_mm(victim);
next prev parent reply other threads:[~2019-02-04 11:03 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-04 10:36 [PATCH 4.14 00/46] 4.14.98-stable review Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 01/46] Fix "net: ipv4: do not handle duplicate fragments as overlapping" Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 02/46] ipv6: Consider sk_bound_dev_if when binding a socket to an address Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 03/46] ipv6: sr: clear IP6CB(skb) on SRH ip4ip6 encapsulation Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 04/46] l2tp: copy 4 more bytes to linear part if necessary Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 05/46] net/mlx4_core: Add masking for a few queries on HCA caps Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 06/46] netrom: switch to sock timer API Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 07/46] net/rose: fix NULL ax25_cb kernel panic Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 08/46] net: set default network namespace in init_dummy_netdev() Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 09/46] ucc_geth: Reset BQL queue when stopping device Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 10/46] net/mlx5e: Allow MAC invalidation while spoofchk is ON Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 11/46] Revert "net/mlx5e: E-Switch, Initialize eswitch only if eswitch manager" Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 12/46] virtio_net: Dont enable NAPI when interface is down Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 13/46] virtio_net: Dont call free_old_xmit_skbs for xdp_frames Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 14/46] virtio_net: Fix not restoring real_num_rx_queues Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 15/46] sctp: improve the events for sctp stream adding Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 16/46] sctp: improve the events for sctp stream reset Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 17/46] l2tp: remove l2specific_len dependency in l2tp_core Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 18/46] l2tp: fix reading optional fields of L2TPv3 Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 19/46] ipvlan, l3mdev: fix broken l3s mode wrt local routes Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 20/46] CIFS: Do not count -ENODATA as failure for query directory Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 21/46] fs/dcache: Fix incorrect nr_dentry_unused accounting in shrink_dcache_sb() Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 22/46] iommu/vt-d: Fix memory leak in intel_iommu_put_resv_regions() Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 23/46] selftests/seccomp: Enhance per-arch ptrace syscall skip tests Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 24/46] NFS: Fix up return value on fatal errors in nfs_page_async_flush() Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 25/46] ARM: cns3xxx: Fix writing to wrong PCI config registers after alignment Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 26/46] arm64: kaslr: ensure randomized quantities are clean also when kaslr is off Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 27/46] arm64: hyp-stub: Forbid kprobing of the hyp-stub Greg Kroah-Hartman
2019-02-04 10:36 ` [PATCH 4.14 28/46] arm64: hibernate: Clean the __hyp_text to PoC after resume Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 29/46] gpio: altera-a10sr: Set proper output level for direction_output Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 30/46] gpio: pcf857x: Fix interrupts on multiple instances Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 31/46] gfs2: Revert "Fix loop in gfs2_rbm_find" Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 32/46] mmc: bcm2835: Fix DMA channel leak on probe error Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 33/46] ALSA: hda/realtek - Fixed hp_pin no value Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 34/46] IB/hfi1: Remove overly conservative VM_EXEC flag check Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 35/46] platform/x86: asus-nb-wmi: Map 0x35 to KEY_SCREENLOCK Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 36/46] platform/x86: asus-nb-wmi: Drop mapping of 0x33 and 0x34 scan codes Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 37/46] mmc: sdhci-iproc: handle mmc_of_parse() errors during probe Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 38/46] kernel/exit.c: release ptraced tasks before zap_pid_ns_processes Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 39/46] oom, oom_reaper: do not enqueue same task twice Greg Kroah-Hartman
2019-02-04 10:37 ` Greg Kroah-Hartman [this message]
2019-02-04 10:37 ` [PATCH 4.14 41/46] mm: hwpoison: use do_send_sig_info() instead of force_sig() Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 42/46] mm: migrate: dont rely on __PageMovable() of newpage after unlocking it Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 43/46] md/raid5: fix out of memory during raid cache recovery Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 44/46] cifs: Always resolve hostname before reconnecting Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 45/46] drivers: core: Remove glue dirs from sysfs earlier Greg Kroah-Hartman
2019-02-04 10:37 ` [PATCH 4.14 46/46] fanotify: fix handling of events on child sub-directory Greg Kroah-Hartman
2019-02-04 21:49 ` [PATCH 4.14 00/46] 4.14.98-stable review Guenter Roeck
2019-02-05 6:38 ` Naresh Kamboju
2019-02-05 10:20 ` Jon Hunter
2019-02-05 14:42 ` Greg Kroah-Hartman
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