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Date:   Thu, 14 Sep 2023 17:24:42 +0300
From:   =?UTF-8?Q?Jos=C3=A9_Pekkarinen?= <jose.pekkarinen@foxhound.fi>
To:     Maxime Ripard <mripard@kernel.org>
Cc:     airlied@gmail.com, daniel@ffwll.ch, christian.koenig@amd.com,
        dakr@redhat.com, boris.brezillon@collabora.com,
        alexander.deucher@amd.com, arthurgrillo@riseup.net,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH] drm/tests: provide exit function
In-Reply-To: <q37ckz3xj6zhuxrrwymw5oda4su7phw5gsgdtlevunhu645wzv@x4pzm6vm7yqt>
References: <20230913083223.28684-1-jose.pekkarinen@foxhound.fi>
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On 2023-09-14 15:00, Maxime Ripard wrote:
> On Wed, Sep 13, 2023 at 07:35:57PM +0300, José Pekkarinen wrote:
>> On 2023-09-13 17:41, mripard@kernel.org wrote:
>> > On Wed, Sep 13, 2023 at 05:01:40PM +0300, José Pekkarinen wrote:
>> > > On 2023-09-13 12:50, Maxime Ripard wrote:
>> > > > Hi,
>> > > >
>> > > > On Wed, Sep 13, 2023 at 11:32:23AM +0300, José Pekkarinen wrote:
>> > > > > Running drm_exec_test by modprobing the module I
>> > > > > observe the following output:
>> > > > >
>> > > > > [  424.471936] KTAP version 1
>> > > > > [  424.471942] 1..1
>> > > > > [  424.472446]     KTAP version 1
>> > > > > [  424.472450]     # Subtest: drm_exec
>> > > > > [  424.472453]     # module: drm_exec_test
>> > > > > [  424.472459]     1..7
>> > > > > [  424.479082]
>> > > > > ==================================================================
>> > > > > [  424.479095] BUG: KASAN: slab-use-after-free in
>> > > > > drm_dev_put.part.0+0x4b/0x90 [drm]
>> > > > > [  424.479426] Read of size 8 at addr ffff888132d3e028 by task
>> > > > > kunit_try_catch/1866
>> > > > > [  424.479436]
>> > > > > [  424.479442] CPU: 1 PID: 1866 Comm: kunit_try_catch Tainted: G
>> > > > > N 6.6.0-rc1-dirty #2
>> > > >
>> > > > That's suspicious
>> > > >
>> > > > > [  424.479446] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009),
>> > > > > BIOS 0.0.0 02/06/2015
>> > > > > [  424.479446] Call Trace:
>> > > > > [  424.479446]  <TASK>
>> > > > > [  424.479446]  dump_stack_lvl+0x43/0x60
>> > > > > [  424.479446]  print_report+0xcf/0x660
>> > > > > [  424.479446]  ? __virt_addr_valid+0xd9/0x160
>> > > > > [  424.479446]  ? drm_dev_put.part.0+0x4b/0x90 [drm]
>> > > > > [  424.479446]  kasan_report+0xda/0x110
>> > > > > [  424.479446]  ? drm_dev_put.part.0+0x4b/0x90 [drm]
>> > > > > [  424.479446]  drm_dev_put.part.0+0x4b/0x90 [drm]
>> > > > > [  424.479446]  release_nodes+0x83/0x160
>> > > > > [  424.479446]  devres_release_all+0xe6/0x130
>> > > > > [  424.479446]  ? __pfx_devres_release_all+0x10/0x10
>> > > > > [  424.479446]  ? mutex_unlock+0x80/0xd0
>> > > > > [  424.479446]  ? __pfx_mutex_unlock+0x10/0x10
>> > > > > [  424.479446]  device_unbind_cleanup+0x16/0xc0
>> > > > > [  424.479446]  device_release_driver_internal+0x28b/0x2e0
>> > > > > [  424.479446]  bus_remove_device+0x124/0x1d0
>> > > > > [  424.479446]  device_del+0x23d/0x580
>> > > > > [  424.479446]  ? __pfx_device_del+0x10/0x10
>> > > > > [  424.479446]  ? kasan_set_track+0x21/0x30
>> > > > > [  424.479446]  ? _raw_spin_lock_irqsave+0x98/0xf0
>> > > > > [  424.479446]  platform_device_del.part.0+0x19/0xe0
>> > > > > [  424.479446]  kunit_remove_resource+0xfa/0x140 [kunit]
>> > > > > [  424.479446]  kunit_cleanup+0x47/0xa0 [kunit]
>> > > > > [  424.479446]  ? __pfx_kunit_try_run_case_cleanup+0x10/0x10 [kunit]
>> > > > > [  424.479446]  ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10
>> > > > > [kunit]
>> > > > > [  424.479446]  kunit_generic_run_threadfn_adapter+0x29/0x50 [kunit]
>> > > > > [  424.479446]  kthread+0x184/0x1c0
>> > > > > [  424.479446]  ? __pfx_kthread+0x10/0x10
>> > > > > [  424.479446]  ret_from_fork+0x30/0x50
>> > > > > [  424.479446]  ? __pfx_kthread+0x10/0x10
>> > > > > [  424.479446]  ret_from_fork_asm+0x1b/0x30
>> > > > > [  424.479446]  </TASK>
>> > > > > [  424.479446]
>> > > > > [  424.479446] Allocated by task 1865:
>> > > > > [  424.479446]  kasan_save_stack+0x2f/0x50
>> > > > > [  424.479446]  kasan_set_track+0x21/0x30
>> > > > > [  424.479446]  __kasan_kmalloc+0xa6/0xb0
>> > > > > [  424.479446]  __kmalloc+0x5d/0x160
>> > > > > [  424.479446]  kunit_kmalloc_array+0x1c/0x50 [kunit]
>> > > > > [  424.479446]  drm_exec_test_init+0xef/0x260 [drm_exec_test]
>> > > > > [  424.479446]  kunit_try_run_case+0x6e/0x100 [kunit]
>> > > > > [  424.479446]  kunit_generic_run_threadfn_adapter+0x29/0x50 [kunit]
>> > > > > [  424.479446]  kthread+0x184/0x1c0
>> > > > > [  424.479446]  ret_from_fork+0x30/0x50
>> > > > > [  424.479446]  ret_from_fork_asm+0x1b/0x30
>> > > > > [  424.479446]
>> > > > > [  424.479446] Freed by task 1866:
>> > > > > [  424.479446]  kasan_save_stack+0x2f/0x50
>> > > > > [  424.479446]  kasan_set_track+0x21/0x30
>> > > > > [  424.479446]  kasan_save_free_info+0x27/0x40
>> > > > > [  424.479446]  ____kasan_slab_free+0x166/0x1c0
>> > > > > [  424.479446]  slab_free_freelist_hook+0x9f/0x1e0
>> > > > > [  424.479446]  __kmem_cache_free+0x187/0x2d0
>> > > > > [  424.479446]  kunit_remove_resource+0xfa/0x140 [kunit]
>> > > > > [  424.479446]  kunit_cleanup+0x47/0xa0 [kunit]
>> > > > > [  424.479446]  kunit_generic_run_threadfn_adapter+0x29/0x50 [kunit]
>> > > > > [  424.479446]  kthread+0x184/0x1c0
>> > > > > [  424.479446]  ret_from_fork+0x30/0x50
>> > > > > [  424.479446]  ret_from_fork_asm+0x1b/0x30
>> > > > > [  424.479446]
>> > > > > [  424.479446] The buggy address belongs to the object at
>> > > > > ffff888132d3e000
>> > > > > [  424.479446]  which belongs to the cache kmalloc-256 of size 256
>> > > > > [  424.479446] The buggy address is located 40 bytes inside of
>> > > > > [  424.479446]  freed 256-byte region [ffff888132d3e000,
>> > > > > ffff888132d3e100)
>> > > > > [  424.479446]
>> > > > > [  424.479446] The buggy address belongs to the physical page:
>> > > > > [  424.479446] page:0000000092ff6551 refcount:1 mapcount:0
>> > > > > mapping:0000000000000000 index:0xffff888132d3f600 pfn:0x132d3c
>> > > > > [  424.479446] head:0000000092ff6551 order:2 entire_mapcount:0
>> > > > > nr_pages_mapped:0 pincount:0
>> > > > > [  424.479446] ksm flags:
>> > > > > 0x17ffffc0000840(slab|head|node=0|zone=2|lastcpupid=0x1fffff)
>> > > > > [  424.479446] page_type: 0xffffffff()
>> > > > > [  424.479446] raw: 0017ffffc0000840 ffff888100042b40
>> > > > > ffffea00042c8000 dead000000000003
>> > > > > [  424.479446] raw: ffff888132d3f600 000000008020001f
>> > > > > 00000001ffffffff 0000000000000000
>> > > > > [  424.479446] page dumped because: kasan: bad access detected
>> > > > > [  424.479446]
>> > > > > [  424.479446] Memory state around the buggy address:
>> > > > > [  424.479446]  ffff888132d3df00: fc fc fc fc fc fc fc fc fc fc fc
>> > > > > fc fc fc fc fc
>> > > > > [  424.479446]  ffff888132d3df80: fc fc fc fc fc fc fc fc fc fc fc
>> > > > > fc fc fc fc fc
>> > > > > [  424.479446] >ffff888132d3e000: fa fb fb fb fb fb fb fb fb fb fb
>> > > > > fb fb fb fb fb
>> > > > > [  424.479446]                                   ^
>> > > > > [  424.479446]  ffff888132d3e080: fb fb fb fb fb fb fb fb fb fb fb
>> > > > > fb fb fb fb fb
>> > > > > [  424.479446]  ffff888132d3e100: fc fc fc fc fc fc fc fc fc fc fc
>> > > > > fc fc fc fc fc
>> > > > > [  424.479446]
>> > > > > ==================================================================
>> > > > > [  424.481686] Disabling lock debugging due to kernel taint
>> > > > > [  424.484124]     not ok 1 sanitycheck
>> > > > > [  424.492981]     ok 2 test_lock
>> > > > > [  424.503610]     ok 3 test_lock_unlock
>> > > > > [  424.515058]     ok 4 test_duplicates
>> > > > > [  424.530453]     ok 5 test_prepare
>> > > > > [  424.539099]     ok 6 test_prepare_array
>> > > > > [  424.550730]     ok 7 test_multiple_loops
>> > > > > [  424.550743] # drm_exec: pass:6 fail:1 skip:0 total:7
>> > > > > [  424.550750] # Totals: pass:6 fail:1 skip:0 total:7
>> > > > > [  424.550756] not ok 5 drm_exec
>> > > > >
>> > > > > The ouptut suggest the init function is allocating a drm_device
>> > > > > that is not being freed. This patch provides the function and
>> > > > > add it to the kunit_suite to produce the following result of
>> > > > > the test:
>> > > > >
>> > > > > [ 3363.342560] KTAP version 1
>> > > > > [ 3363.342571] 1..1
>> > > > > [ 3363.343090]     KTAP version 1
>> > > > > [ 3363.343095]     # Subtest: drm_exec
>> > > > > [ 3363.343098]     # module: drm_exec_test
>> > > > > [ 3363.343103]     1..7
>> > > > > [ 3363.353659]     ok 1 sanitycheck
>> > > > > [ 3363.364281]     ok 2 test_lock
>> > > > > [ 3363.375616]     ok 3 test_lock_unlock
>> > > > > [ 3363.388741]     ok 4 test_duplicates
>> > > > > [ 3363.402544]     ok 5 test_prepare
>> > > > > [ 3363.413163]     ok 6 test_prepare_array
>> > > > > [ 3363.424614]     ok 7 test_multiple_loops
>> > > > > [ 3363.424630] # drm_exec: pass:7 fail:0 skip:0 total:7
>> > > > > [ 3363.424637] # Totals: pass:7 fail:0 skip:0 total:7
>> > > > > [ 3363.424643] ok 1 drm_exec
>> > > > >
>> > > > > Signed-off-by: José Pekkarinen <jose.pekkarinen@foxhound.fi>
>> > > > > ---
>> > > > >  drivers/gpu/drm/tests/drm_exec_test.c | 14 ++++++++++++++
>> > > > >  1 file changed, 14 insertions(+)
>> > > > >
>> > > > > diff --git a/drivers/gpu/drm/tests/drm_exec_test.c
>> > > > > b/drivers/gpu/drm/tests/drm_exec_test.c
>> > > > > index 563949d777dd..7ff6bc6467d4 100644
>> > > > > --- a/drivers/gpu/drm/tests/drm_exec_test.c
>> > > > > +++ b/drivers/gpu/drm/tests/drm_exec_test.c
>> > > > > @@ -42,6 +42,19 @@ static int drm_exec_test_init(struct kunit *test)
>> > > > >  	return 0;
>> > > > >  }
>> > > > >
>> > > > > +static void drm_exec_test_exit(struct kunit *test)
>> > > > > +{
>> > > > > +	struct drm_exec_priv *priv = test->priv;
>> > > > > +
>> > > > > +	drm_kunit_helper_free_device(test, priv->dev);
>> > > > > +	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, priv->dev);
>> > > >
>> > > > This shouldn't be necessary at all since 4f2b0b583baa.
>> > >
>> > >
>> > > Reading this suggested patch I see only references to
>> > > platform_driver_unregister, platform_device_put, and
>> > > platform_device_del, not the ones used in this patch.
>> >
>> > I mean, what is drm_kunit_helper_free_device calling?
>> 
>>     That seems to be triggering any registered release
>> action immediately, so it calls platform_device_del,
>> followed by platform_device_put, followed by
>> platform_driver_unregister.
> 
> 
> Please test with:
> https://lore.kernel.org/all/20230907135339.7971-2-thomas.hellstrom@linux.intel.com/
> 
> Maxime

     Hi,

     Yes, I was looking into that road, but Thomas
was faster, here is the output of my tests after
applying Thomas patch:

[  874.063255] KTAP version 1
[  874.063262] 1..1
[  874.064550]     KTAP version 1
[  874.064555]     # Subtest: drm_modes_analog_tv
[  874.064559]     # module: drm_modes_test
[  874.064565]     1..4
[  874.076778]     ok 1 drm_test_modes_analog_tv_ntsc_480i
[  874.091584]     ok 2 drm_test_modes_analog_tv_ntsc_480i_inlined
[  874.104682]     ok 3 drm_test_modes_analog_tv_pal_576i
[  874.116266]     ok 4 drm_test_modes_analog_tv_pal_576i_inlined
[  874.116285] # drm_modes_analog_tv: pass:4 fail:0 skip:0 total:4
[  874.116297] # Totals: pass:4 fail:0 skip:0 total:4
[  874.116305] ok 1 drm_modes_analog_tv
[  888.785690] KTAP version 1
[  888.785697] 1..1
[  888.786186]     KTAP version 1
[  888.786192]     # Subtest: drm_exec
[  888.786196]     # module: drm_exec_test
[  888.786202]     1..7
[  888.796416]     ok 1 sanitycheck
[  888.807215]     ok 2 test_lock
[  888.820305]     ok 3 test_lock_unlock
[  888.829242]     ok 4 test_duplicates
[  888.840362]     ok 5 test_prepare
[  888.851022]     ok 6 test_prepare_array
[  888.865011]     ok 7 test_multiple_loops
[  888.865034] # drm_exec: pass:7 fail:0 skip:0 total:7
[  888.865044] # Totals: pass:7 fail:0 skip:0 total:7
[  888.865053] ok 2 drm_exec

Tested-by: José Pekkarinen<jose.pekkarinen@foxhound.fi>

     Thanks!

     José.