On Thu, May 31, 2018 at 9:18 AM, Dongsheng Yang
<dongsheng.yang@xxxxxxxxxxxx> wrote:
>
> On 05/31/2018 03:11 AM, Ilya Dryomov wrote:
>>
>> On Tue, May 29, 2018 at 5:22 AM, Dongsheng Yang
>> <dongsheng.yang@xxxxxxxxxxxx> wrote:
>>>
>>> We will cancel all watch delayed work in
>>> cancel_delayed_work_sync(&rbd_dev->watch_dwork);
>>> If we queue delayed work after this, there will be a use-after-free
>>> problem:
>>>
>>> [ 549.932085] BUG: unable to handle kernel NULL pointer dereference at
>>> 0000000000000000
>>> [ 549.934134] PGD 0 P4D 0
>>> [ 549.935145] Oops: 0000 [#1] SMP PTI
>>> [ 549.936283] Modules linked in: rbd(OE) libceph(OE) tcp_diag udp_diag
>>> inet_diag unix_diag af_packet_diag netlink_diag dns_resolver ebtable_filter
>>> ebtables ip6table_filter ip6_tables iptable_filter sg cfg80211 rfkill
>>> snd_hda_codec_generic ext4 snd_hda_intel snd_hda_codec crct10dif_pclmul
>>> crc32_pclmul ghash_clmulni_intel snd_hda_core pcbc snd_hwdep snd_seq mbcache
>>> aesni_intel snd_seq_device jbd2 crypto_simd nfsd cryptd glue_helper snd_pcm
>>> snd_timer auth_rpcgss pcspkr snd virtio_balloon nfs_acl soundcore i2c_piix4
>>> lockd grace sunrpc ip_tables xfs libcrc32c virtio_console virtio_blk
>>> ata_generic pata_acpi 8139too qxl drm_kms_helper syscopyarea sysfillrect
>>> sysimgblt fb_sys_fops ttm drm ata_piix libata crc32c_intel virtio_pci 8139cp
>>> virtio_ring i2c_core mii virtio floppy serio_raw dm_mirror dm_region_hash
>>> [ 549.951835] dm_log dm_mod dax [last unloaded: libceph]
>>> [ 549.953490] CPU: 7 PID: 0 Comm: swapper/7 Tainted: G OE
>>> 4.17.0-rc6+ #13
>>> [ 549.955502] Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
>>> [ 549.957246] RIP: 0010:__queue_work+0x6a/0x3b0
>>> [ 549.958744] RSP: 0018:ffff9427df1c3e90 EFLAGS: 00010086
>>> [ 549.960374] RAX: ffff9427deca8400 RBX: 0000000000000000 RCX:
>>> 0000000000000000
>>> [ 549.962297] RDX: ffff9427deca8400 RSI: ffff9427df1c3e50 RDI:
>>> 0000000000000000
>>> [ 549.964216] RBP: ffff942783e39e00 R08: ffff9427deca8400 R09:
>>> ffff9427df1c3f00
>>> [ 549.966136] R10: 0000000000000004 R11: 0000000000000005 R12:
>>> ffff9427cfb85970
>>> [ 549.968070] R13: 0000000000002000 R14: 000000000001eca0 R15:
>>> 0000000000000007
>>> [ 549.969999] FS: 0000000000000000(0000) GS:ffff9427df1c0000(0000)
>>> knlGS:0000000000000000
>>> [ 549.972069] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>> [ 549.973775] CR2: 0000000000000000 CR3: 00000004c900a005 CR4:
>>> 00000000000206e0
>>> [ 549.975695] Call Trace:
>>> [ 549.976900] <IRQ>
>>> [ 549.978033] ? __queue_work+0x3b0/0x3b0
>>> [ 549.979442] call_timer_fn+0x2d/0x130
>>> [ 549.980824] run_timer_softirq+0x16e/0x430
>>> [ 549.982263] ? tick_sched_timer+0x37/0x70
>>> [ 549.983691] __do_softirq+0xd2/0x280
>>> [ 549.985035] irq_exit+0xd5/0xe0
>>> [ 549.986316] smp_apic_timer_interrupt+0x6c/0x130
>>> [ 549.987835] apic_timer_interrupt+0xf/0x20
>>>
>>> This patch forbid to queue watch_dwork when we are removing device.
>>>
>>> Signed-off-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
>>> ---
>>> drivers/block/rbd.c | 10 +++++++---
>>> 1 file changed, 7 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
>>> index 2b4e90d..d1d8f46 100644
>>> --- a/drivers/block/rbd.c
>>> +++ b/drivers/block/rbd.c
>>> @@ -3475,9 +3475,13 @@ static void rbd_reregister_watch(struct
>>> work_struct *work)
>>> set_bit(RBD_DEV_FLAG_BLACKLISTED,
>>> &rbd_dev->flags);
>>> wake_requests(rbd_dev, true);
>>> } else {
>>> - queue_delayed_work(rbd_dev->task_wq,
>>> - &rbd_dev->watch_dwork,
>>> - RBD_RETRY_DELAY);
>>> + spin_lock_irq(&rbd_dev->lock);
>>> + if (!test_bit(RBD_DEV_FLAG_REMOVING,
>>> &rbd_dev->flags)) {
>>> + queue_delayed_work(rbd_dev->task_wq,
>>> + &rbd_dev->watch_dwork,
>>> + RBD_RETRY_DELAY);
>>> + }
>>> + spin_unlock_irq(&rbd_dev->lock);
>>> }
>>> mutex_unlock(&rbd_dev->watch_mutex);
>>> return;
>>
>> Hi Dongsheng,
>>
>> What made you think it is rbd (or ceph) related? Do you know what gets
>> dereferenced? Is it reproducible?
>
>
> Hi Ilya,
> There is a simple reproduce script:
>
> ./vstart.sh -k -l --bluestore
> rbd map -o osd_request_timeout=10 test1
> time dd if=/dev/zero of=/dev/rbd0 bs=64K count=1000 oflag=direct &
> sleep 1
> ps -ef|grep -E "ceph-mon|ceph-osd"|gawk '{print "kill -9 "$2}'|bash
> rbd unmap -o force /dev/rbd0
>
> But maybe you need to run this script in a loop, because that's not 100%
> happen.
Ah, I see. I think a more correct fix would be to move ->watch_dwork
cancellation:
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 2b4e90d06822..23ae0df7a978 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -3400,7 +3400,6 @@ static void cancel_tasks_sync(struct rbd_device *rbd_dev)
{
dout("%s rbd_dev %p\n", __func__, rbd_dev);
- cancel_delayed_work_sync(&rbd_dev->watch_dwork);
cancel_work_sync(&rbd_dev->acquired_lock_work);
cancel_work_sync(&rbd_dev->released_lock_work);
cancel_delayed_work_sync(&rbd_dev->lock_dwork);
@@ -3418,6 +3417,7 @@ static void rbd_unregister_watch(struct
rbd_device *rbd_dev)
rbd_dev->watch_state = RBD_WATCH_STATE_UNREGISTERED;
mutex_unlock(&rbd_dev->watch_mutex);
+ cancel_delayed_work_sync(&rbd_dev->watch_dwork);
ceph_osdc_flush_notifies(&rbd_dev->rbd_client->client->osdc);
}
This way rbd_reregister_watch() should either bail out early because
the watch is UNREGISTERED at that point or just get cancelled.
Thanks,
Ilya
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