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From: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
Cc: Daniel Vetter <daniel@ffwll.ch>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>,
	intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [Intel-xe] [PATCH 1/3] drm/kunit: Avoid a driver uaf
Date: Tue, 5 Sep 2023 14:43:00 +0200	[thread overview]
Message-ID: <0cb8a51c-a1a8-ba03-03b1-8cdabade0353@linux.intel.com> (raw)
In-Reply-To: <efarj6smmvuqlredgy5aelgvm43xovnqo5fywsindq3bhggvul@3rqq27vmatcm>

Hi maxime,

On 9/5/23 14:06, Maxime Ripard wrote:
> On Tue, Sep 05, 2023 at 10:58:30AM +0200, Thomas Hellström wrote:
>> when using __drm_kunit_helper_alloc_drm_device() the driver may be
>> dereferenced by device-managed resources up until the device is
>> freed, which is typically later than the kunit-managed resource code
>> frees it.
> I'd like to have a bit more context on how a driver can end up in that
> situation?

I interpret the attached traces as follows.

INIT:

Code allocates a struct device as a kunit-managed resource.
Code allocates a drm driver as a kunit-managed resource.
Code allocates a drm device as a device-managed resource.

EXIT:

Kunit resource cleanup frees the drm driver
Kunit resource cleanup frees the struct device, which starts a 
device-managed resource cleanup
device-managed cleanup calls drm_dev_put()
drm_dev_put() dereferences the (now freed) drm driver -> Boom.

It should be sufficient to enable KASAN and run the drm_exec_test kunit 
test to trigger this.

Thanks,
Thomas


>
> Maxime

WARNING: multiple messages have this Message-ID (diff)
From: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>,
	intel-xe@lists.freedesktop.org, dri-devel@lists.freedesktop.org
Subject: Re: [Intel-xe] [PATCH 1/3] drm/kunit: Avoid a driver uaf
Date: Tue, 5 Sep 2023 14:43:00 +0200	[thread overview]
Message-ID: <0cb8a51c-a1a8-ba03-03b1-8cdabade0353@linux.intel.com> (raw)
In-Reply-To: <efarj6smmvuqlredgy5aelgvm43xovnqo5fywsindq3bhggvul@3rqq27vmatcm>

Hi maxime,

On 9/5/23 14:06, Maxime Ripard wrote:
> On Tue, Sep 05, 2023 at 10:58:30AM +0200, Thomas Hellström wrote:
>> when using __drm_kunit_helper_alloc_drm_device() the driver may be
>> dereferenced by device-managed resources up until the device is
>> freed, which is typically later than the kunit-managed resource code
>> frees it.
> I'd like to have a bit more context on how a driver can end up in that
> situation?

I interpret the attached traces as follows.

INIT:

Code allocates a struct device as a kunit-managed resource.
Code allocates a drm driver as a kunit-managed resource.
Code allocates a drm device as a device-managed resource.

EXIT:

Kunit resource cleanup frees the drm driver
Kunit resource cleanup frees the struct device, which starts a 
device-managed resource cleanup
device-managed cleanup calls drm_dev_put()
drm_dev_put() dereferences the (now freed) drm driver -> Boom.

It should be sufficient to enable KASAN and run the drm_exec_test kunit 
test to trigger this.

Thanks,
Thomas


>
> Maxime

  reply	other threads:[~2023-09-05 12:43 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-09-05  8:58 [Intel-xe] [PATCH 0/3] drm/drm_exec, drm/drm_kunit: Fix / WA for uaf and lock alloc tracking Thomas Hellström
2023-09-05  8:58 ` Thomas Hellström
2023-09-05  8:58 ` [Intel-xe] [PATCH 1/3] drm/kunit: Avoid a driver uaf Thomas Hellström
2023-09-05  8:58   ` Thomas Hellström
2023-09-05 12:06   ` [Intel-xe] " Maxime Ripard
2023-09-05 12:06     ` Maxime Ripard
2023-09-05 12:43     ` Thomas Hellström [this message]
2023-09-05 12:43       ` Thomas Hellström
2023-09-06 10:08       ` Maxime Ripard
2023-09-06 10:08         ` Maxime Ripard
2023-09-07 10:32         ` Thomas Hellström
2023-09-07 10:32           ` Thomas Hellström
2023-09-05  8:58 ` [Intel-xe] [PATCH 2/3] drm/tests/drm_exec: Add a test for object freeing within drm_exec_fini() Thomas Hellström
2023-09-05  8:58   ` Thomas Hellström
2023-09-05 12:05   ` [Intel-xe] " Maxime Ripard
2023-09-05 12:32     ` Thomas Hellström
2023-09-05 13:16       ` Maxime Ripard
2023-09-05 13:42         ` Thomas Hellström
2023-09-06 10:07           ` Maxime Ripard
2023-09-06 10:07             ` Maxime Ripard
2023-09-05  8:58 ` [Intel-xe] [PATCH 3/3] drm/drm_exec: Work around a WW mutex lockdep oddity Thomas Hellström
2023-09-05  8:58   ` Thomas Hellström
2023-09-05  9:22   ` [Intel-xe] " Boris Brezillon
2023-09-05  9:22     ` Boris Brezillon
2023-09-05 10:59   ` [Intel-xe] " Danilo Krummrich
2023-09-05 10:59     ` Danilo Krummrich
2023-09-05 13:14   ` [Intel-xe] " Christian König
2023-09-05 13:14     ` Christian König
2023-09-05 14:29     ` [Intel-xe] " Thomas Hellström
2023-09-05 14:29       ` Thomas Hellström
2023-09-06  8:34       ` [Intel-xe] " Christian König
2023-09-06  8:34         ` Christian König
2023-09-07  8:59         ` [Intel-xe] " Thomas Hellström
2023-09-07  8:59           ` Thomas Hellström
2023-09-05  9:01 ` [Intel-xe] ✓ CI.Patch_applied: success for drm/drm_exec, drm/drm_kunit: Fix / WA for uaf and lock alloc tracking Patchwork
2023-09-05  9:01 ` [Intel-xe] ✗ CI.checkpatch: warning " Patchwork
2023-09-05  9:03 ` [Intel-xe] ✓ CI.KUnit: success " Patchwork
2023-09-05  9:10 ` [Intel-xe] ✓ CI.Build: " Patchwork
2023-09-05  9:10 ` [Intel-xe] ✗ CI.Hooks: failure " Patchwork
2023-09-05  9:10 ` [Intel-xe] ✗ CI.checksparse: warning " Patchwork
2023-09-07 14:52 ` [Intel-xe] ✗ CI.Patch_applied: failure for drm/drm_exec, drm/drm_kunit: Fix / WA for uaf and lock alloc tracking. (rev2) Patchwork

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