Re: [PATCH] drm/tests: provide exit function

From: José Pekkarinen
Date: Wed Sep 13 2023 - 12:47:59 EST

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On 2023-09-13 17:41, mripard@xxxxxxxxxx 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@xxxxxxxxxxx>
> > ---
> > 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. Reducing the patch to
just call the drm_dev_put that doesn't seem to happen
automatically still triggers this stacktrace:

[ 3300.409436] refcount_t: underflow; use-after-free.
[ 3300.409483] WARNING: CPU: 6 PID: 13758 at lib/refcount.c:28 refcount_warn_saturate+0xcd/0x120
[ 3300.409504] Modules linked in: drm_exec_test drm_exec drm_kunit_helpers kunit snd_usb_audio snd_usbmidi_lib uvcvideo snd_ump snd_hwdep videobuf2_vmalloc snd_pcm videobuf2_memops snd
_rawmidi uvc videobuf2_v4l2 snd_seq_device snd_timer videodev snd soundcore videobuf2_common mc rfkill binfmt_misc intel_rapl_msr intel_rapl_common kvm_amd ccp rng_core kvm nls_ascii irqbypass nls_cp437 crct10dif_pclmul crct10dif_common
vfat crc32_pclmul fat ghash_clmulni_intel sha512_ssse3 sha512_generic aesni_intel crypto_simd cryptd iTCO_wdt pcspkr intel_pmc_bxt virtio_console iTCO_vendor_support intel_agp joydev evdev intel_gtt watchdog button serio_raw sg nft_ct
msr nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 parport_pc nf_tables ppdev lp libcrc32c parport nfnetlink loop fuse efi_pstore configfs efivarfs qemu_fw_cfg ip_tables x_tables autofs4 ext4 crc32c_generic crc16 mbcache jbd2 hid_generic us
bhid hid dm_mod virtio_gpu virtio_dma_buf drm_shmem_helper drm_kms_helper sr_mod virtio_net cdrom net_failover drm failover virtio_blk ahci
2023-09-13T18:21:01.438934+03:00 woodpecker kernel: [ 3300.410013] libahci virtio_pci libata xhci_pci virtio xhci_hcd i2c_i801 crc32c_intel virtio_pci_legacy_dev scsi_mod usbcore virtio_pci_modern_dev psmouse i2c_smbus scsi_common lpc_
ich usb_common virtio_ring
[ 3300.410081] CPU: 6 PID: 13758 Comm: kunit_try_catch Tainted: G B N 6.6.0-rc1+ #3
[ 3300.410092] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[ 3300.410098] RIP: 0010:refcount_warn_saturate+0xcd/0x120
[ 3300.410113] Code: 0a 21 fc 01 01 e8 03 9d 7f ff 0f 0b eb 95 80 3d f9 20 fc 01 00 75 8c 48 c7 c7 e0 10 a8 b9 c6 05 e9 20 fc 01 01 e8 e3 9c 7f ff <0f> 0b e9 72 ff ff ff 80 3d d4 20 fc
01 00 0f 85 65 ff ff ff 48 c7
[ 3300.410122] RSP: 0018:ffff888284397bf0 EFLAGS: 00010286
[ 3300.410132] RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000
[ 3300.410138] RDX: 0000000000000002 RSI: ffffffffb8567c64 RDI: ffffffffbb90c7a0
[ 3300.410145] RBP: ffff888271e3d004 R08: 0000000000000001 R09: ffffed1062726081
[ 3300.410151] R10: ffff88831393040b R11: 0000000000000001 R12: ffff888124145c80
[ 3300.410158] R13: ffff888284397c78 R14: ffffffffc0c11b20 R15: 0000000000000010
[ 3300.410168] FS: 0000000000000000(0000) GS:ffff888313900000(0000) knlGS:0000000000000000
[ 3300.410176] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 3300.410182] CR2: 00007ffdbe910148 CR3: 0000000119c3c000 CR4: 0000000000350ee0
[ 3300.410191] Call Trace:
[ 3300.410197] <TASK>
[ 3300.410203] ? __warn+0xa1/0x1a0
[ 3300.410221] ? refcount_warn_saturate+0xcd/0x120
[ 3300.410239] ? report_bug+0x1f2/0x220
[ 3300.410258] ? handle_bug+0x41/0x80
[ 3300.410272] ? exc_invalid_op+0x13/0x40
[ 3300.410285] ? asm_exc_invalid_op+0x16/0x20
[ 3300.410304] ? preempt_count_sub+0x14/0xc0
[ 3300.410316] ? refcount_warn_saturate+0xcd/0x120
[ 3300.410323] release_nodes+0x83/0x160
[ 3300.410332] devres_release_all+0xe6/0x130
[ 3300.410338] ? __pfx_devres_release_all+0x10/0x10
[ 3300.410343] ? mutex_unlock+0x80/0xd0
[ 3300.410349] ? __pfx_mutex_unlock+0x10/0x10
[ 3300.410356] device_unbind_cleanup+0x16/0xc0
[ 3300.410364] device_release_driver_internal+0x28b/0x2e0
[ 3300.410372] bus_remove_device+0x124/0x1d0
[ 3300.410378] device_del+0x23d/0x580
[ 3300.410384] ? __pfx_device_del+0x10/0x10
[ 3300.410389] ? kasan_set_track+0x21/0x30
[ 3300.410395] ? _raw_spin_lock_irqsave+0x98/0xf0
[ 3300.410402] platform_device_del.part.0+0x19/0xe0
[ 3300.410408] kunit_remove_resource+0xfa/0x140 [kunit]
[ 3300.410427] kunit_cleanup+0x47/0xa0 [kunit]
[ 3300.410443] ? __pfx_kunit_try_run_case_cleanup+0x10/0x10 [kunit]
[ 3300.410460] ? __pfx_kunit_generic_run_threadfn_adapter+0x10/0x10 [kunit]
[ 3300.410477] kunit_generic_run_threadfn_adapter+0x29/0x50 [kunit]
[ 3300.410494] kthread+0x184/0x1c0
[ 3300.410499] ? __pfx_kthread+0x10/0x10
[ 3300.410503] ret_from_fork+0x30/0x50
[ 3300.410509] ? __pfx_kthread+0x10/0x10
[ 3300.410513] ret_from_fork_asm+0x1b/0x30
[ 3300.410522] </TASK>
[ 3300.410524] ---[ end trace 0000000000000000 ]---
[ 3300.411310] ok 1 sanitycheck
[ 3300.422160] ok 2 test_lock
[ 3300.433030] ok 3 test_lock_unlock
[ 3300.443877] ok 4 test_duplicates
[ 3300.454591] ok 5 test_prepare
[ 3300.467181] ok 6 test_prepare_array
[ 3300.479030] ok 7 test_multiple_loops
[ 3300.479052] # drm_exec: pass:7 fail:0 skip:0 total:7
[ 3300.479065] # Totals: pass:7 fail:0 skip:0 total:7
[ 3300.479076] ok 1 drm_exec

Thanks!

José.

Next message: Ian Abbott: "Re: [PATCH v2 04/13] comedi: comedi_8254: Conditionally remove I/O port support"
Previous message: Christian Brauner: "Re: [PATCH] overlayfs: set ctime when setting mtime and atime"
In reply to: mripard: "Re: [PATCH] drm/tests: provide exit function"
Next in thread: Maxime Ripard: "Re: [PATCH] drm/tests: provide exit function"
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