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Date: Fri, 28 Sep 2018 17:59:00 +0300
From: Ido Schimmel <idosch@...sch.org>
To: Cong Wang <xiyou.wangcong@...il.com>
Cc: netdev@...r.kernel.org, jiri@...nulli.us, jhs@...atatu.com,
Vlad Buslov <vladbu@...lanox.com>
Subject: Re: [Patch net-next v3] net_sched: change tcf_del_walker() to take
idrinfo->lock
On Wed, Sep 19, 2018 at 04:37:29PM -0700, Cong Wang wrote:
> From: Vlad Buslov <vladbu@...lanox.com>
>
> From: Vlad Buslov <vladbu@...lanox.com>
>
> Action API was changed to work with actions and action_idr in concurrency
> safe manner, however tcf_del_walker() still uses actions without taking a
> reference or idrinfo->lock first, and deletes them directly, disregarding
> possible concurrent delete.
>
> Change tcf_del_walker() to take idrinfo->lock while iterating over actions
> and use new tcf_idr_release_unsafe() to release them while holding the
> lock.
>
> And the blocking function fl_hw_destroy_tmplt() could be called when we
> put a filter chain, so defer it to a work queue.
I'm getting a use-after-free when running tc_chains.sh selftest and I
believe it's caused by this patch.
To reproduce:
# cd tools/testing/selftests/net/forwarding
# export TESTS="template_filter_fits"; ./tc_chains.sh veth0 veth1
__tcf_chain_put()
tc_chain_tmplt_del()
fl_tmplt_destroy()
tcf_queue_work(&tmplt->rwork, fl_tmplt_destroy_work)
tcf_chain_destroy()
kfree(chain)
Some time later fl_tmplt_destroy_work() starts executing and
dereferencing 'chain'.
Splat:
[ 48.269074] ==================================================================
[ 48.270186] BUG: KASAN: use-after-free in fl_tmplt_destroy_work+0x289/0x2d0
[ 48.271199] Read of size 8 at addr ffff880067f0d498 by task kworker/u2:1/18
[ 48.272270]
[ 48.272520] CPU: 0 PID: 18 Comm: kworker/u2:1 Not tainted 4.19.0-rc5-custom+ #917
[ 48.273683] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20180531_142017-buildhw-08.phx2.fedoraproject.org-1.fc28 04/01/2014
[ 48.275495] Workqueue: tc_filter_workqueue fl_tmplt_destroy_work
[ 48.276387] Call Trace:
[ 48.276766] dump_stack+0x10f/0x1d8
[ 48.277302] ? dump_stack_print_info.cold.0+0x20/0x20
[ 48.278080] ? printk+0xac/0xd4
[ 48.278585] ? cpumask_weight.constprop.23+0x39/0x39
[ 48.279360] print_address_description.cold.3+0x9/0x258
[ 48.280186] kasan_report.cold.4+0x6a/0x9d
[ 48.280856] __asan_report_load8_noabort+0x19/0x20
[ 48.281642] fl_tmplt_destroy_work+0x289/0x2d0
[ 48.282331] ? fl_tmplt_destroy+0x30/0x30
[ 48.282966] process_one_work+0xb5d/0x1a10
[ 48.283642] ? kasan_check_write+0x14/0x20
[ 48.284301] ? pwq_dec_nr_in_flight+0x4e0/0x4e0
[ 48.285003] ? lock_repin_lock+0x360/0x360
[ 48.285652] ? __schedule+0x86d/0x2310
[ 48.286256] ? lockdep_hardirqs_on+0x39f/0x580
[ 48.286995] ? __sched_text_start+0x8/0x8
[ 48.287654] ? lock_downgrade+0x740/0x740
[ 48.288292] ? sched_clock_local+0xe0/0x150
[ 48.288969] ? save_trace+0x340/0x340
[ 48.289526] ? save_trace+0x340/0x340
[ 48.290156] ? check_preemption_disabled+0x3b/0x210
[ 48.290937] ? find_held_lock+0x40/0x1d0
[ 48.291598] ? debug_smp_processor_id+0x1c/0x20
[ 48.292290] ? worker_thread+0x3c3/0x12b0
[ 48.292952] ? lock_contended+0x1260/0x1260
[ 48.293606] ? _raw_spin_unlock_irq+0x2c/0x50
[ 48.294311] ? do_raw_spin_trylock+0x121/0x1c0
[ 48.294982] ? do_raw_spin_lock+0x1e0/0x1e0
[ 48.295658] ? trace_hardirqs_on+0x290/0x290
[ 48.296346] worker_thread+0x18e/0x12b0
[ 48.296972] ? lock_repin_lock+0x360/0x360
[ 48.297624] ? process_one_work+0x1a10/0x1a10
[ 48.298332] ? save_trace+0x340/0x340
[ 48.298937] ? kasan_check_write+0x14/0x20
[ 48.299639] ? sched_clock_local+0xe0/0x150
[ 48.300310] ? check_preemption_disabled+0x3b/0x210
[ 48.301064] ? check_preemption_disabled+0x3b/0x210
[ 48.301848] ? find_held_lock+0x40/0x1d0
[ 48.302472] ? debug_smp_processor_id+0x1c/0x20
[ 48.303196] ? _raw_spin_unlock_irqrestore+0x57/0x70
[ 48.304037] ? _raw_spin_unlock_irqrestore+0x57/0x70
[ 48.304862] ? lockdep_hardirqs_on+0x39f/0x580
[ 48.305595] ? trace_hardirqs_on+0xa1/0x290
[ 48.306237] ? do_raw_spin_trylock+0x121/0x1c0
[ 48.306924] ? __kthread_parkme+0xdc/0x1a0
[ 48.307607] ? preempt_schedule_common+0x1f/0xd0
[ 48.308359] ? __kthread_parkme+0x5d/0x1a0
[ 48.309014] ? __kthread_parkme+0xfa/0x1a0
[ 48.309690] ? _raw_spin_unlock_irqrestore+0x60/0x70
[ 48.310461] kthread+0x34d/0x410
[ 48.310970] ? process_one_work+0x1a10/0x1a10
[ 48.311672] ? kthread_delayed_work_timer_fn+0x450/0x450
[ 48.312548] ret_from_fork+0x24/0x30
[ 48.313114]
[ 48.313390] Allocated by task 1239:
[ 48.313983] save_stack+0x43/0xd0
[ 48.314533] kasan_kmalloc+0xc4/0xe0
[ 48.315119] kmem_cache_alloc_trace+0x124/0x280
[ 48.315873] tcf_chain_create+0xa4/0x370
[ 48.316506] tc_ctl_chain+0xe3d/0x1430
[ 48.317114] rtnetlink_rcv_msg+0x3a3/0xa80
[ 48.317799] netlink_rcv_skb+0x152/0x3c0
[ 48.318440] rtnetlink_rcv+0x21/0x30
[ 48.319042] netlink_unicast+0x52f/0x740
[ 48.319675] netlink_sendmsg+0x9c7/0xf50
[ 48.320276] sock_sendmsg+0xcf/0x120
[ 48.320853] ___sys_sendmsg+0x778/0x8f0
[ 48.321445] __sys_sendmsg+0x112/0x270
[ 48.322079] __x64_sys_sendmsg+0x7d/0xc0
[ 48.322687] do_syscall_64+0x15d/0x640
[ 48.323274] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 48.324004]
[ 48.324264] Freed by task 1248:
[ 48.324796] save_stack+0x43/0xd0
[ 48.314533] kasan_kmalloc+0xc4/0xe0
[ 48.315119] kmem_cache_alloc_trace+0x124/0x280
[ 48.315873] tcf_chain_create+0xa4/0x370
[ 48.316506] tc_ctl_chain+0xe3d/0x1430
[ 48.317114] rtnetlink_rcv_msg+0x3a3/0xa80
[ 48.317799] netlink_rcv_skb+0x152/0x3c0
[ 48.318440] rtnetlink_rcv+0x21/0x30
[ 48.319042] netlink_unicast+0x52f/0x740
[ 48.319675] netlink_sendmsg+0x9c7/0xf50
[ 48.320276] sock_sendmsg+0xcf/0x120
[ 48.320853] ___sys_sendmsg+0x778/0x8f0
[ 48.321445] __sys_sendmsg+0x112/0x270
[ 48.322079] __x64_sys_sendmsg+0x7d/0xc0
[ 48.322687] do_syscall_64+0x15d/0x640
[ 48.323274] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 48.324004]
[ 48.324264] Freed by task 1248:
[ 48.324796] save_stack+0x43/0xd0
[ 48.325355] __kasan_slab_free+0x131/0x180
[ 48.326001] kasan_slab_free+0xe/0x10
[ 48.326579] kfree+0xd7/0x2b0
[ 48.327054] __tcf_chain_put+0x339/0x710
[ 48.327654] tc_ctl_chain+0xbde/0x1430
[ 48.328276] rtnetlink_rcv_msg+0x3a3/0xa80
[ 48.328899] netlink_rcv_skb+0x152/0x3c0
[ 48.329556] rtnetlink_rcv+0x21/0x30
[ 48.330170] netlink_unicast+0x52f/0x740
[ 48.330839] netlink_sendmsg+0x9c7/0xf50
[ 48.331491] sock_sendmsg+0xcf/0x120
[ 48.332079] ___sys_sendmsg+0x778/0x8f0
[ 48.332706] __sys_sendmsg+0x112/0x270
[ 48.333334] __x64_sys_sendmsg+0x7d/0xc0
[ 48.333957] do_syscall_64+0x15d/0x640
[ 48.334581] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 48.335362]
[ 48.335645] The buggy address belongs to the object at ffff880067f0d480
[ 48.335645] which belongs to the cache kmalloc-64 of size 64
[ 48.337559] The buggy address is located 24 bytes inside of
[ 48.337559] 64-byte region [ffff880067f0d480, ffff880067f0d4c0)
[ 48.339313] The buggy address belongs to the page:
[ 48.340083] page:ffffea00019fc340 count:1 mapcount:0 mapping:ffff88006cc01780 index:0x0
[ 48.341330] flags: 0x100000000000100(slab)
[ 48.342000] raw: 0100000000000100 ffffea00019fce80 0000001100000011 ffff88006cc01780
[ 48.343163] raw: 0000000000000000 00000000002a002a 00000001ffffffff 0000000000000000
[ 48.344424] page dumped because: kasan: bad access detected
[ 48.345299]
[ 48.345580] Memory state around the buggy address:
[ 48.346356] ffff880067f0d380: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
[ 48.347477] ffff880067f0d400: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
[ 48.348645] >ffff880067f0d480: fb fb fb fb fb fb fb fb fc fc fc fc fb fb fb fb
[ 48.349799] ^
[ 48.350457] ffff880067f0d500: fb fb fb fb fc fc fc fc fb fb fb fb fb fb fb fb
[ 48.351627] ffff880067f0d580: fc fc fc fc fb fb fb fb fb fb fb fb fc fc fc fc
[ 48.352802] ==================================================================
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