[PATCH] drm/amd/scheduler: fix one used-after-free case for job->s_entity

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> But immediately you call "sched_job = amd_sched_entity_peek_job(entity)", keep in mind that this point the "entity" may
> Already be a wild pointer, since above "sched_select_entity' unlock the RQ's spinlock
No, that is unproblematic. The entity won't be freed until all its jobs 
are freed.

> For gpu reset feature, it's more complicated, because in run_job() routine we need check entity's guilty pointer, but that time
> The entity from sched_job->s_entity may also already a wild pointer
Crap, that is indeed a problem. We should probably rather move that 
check into amd_sched_entity_pop_job().

Problem is that we can't check the entity then again during job 
recovery. Need to take a second look at this.

Christian.

Am 24.10.2017 um 12:17 schrieb Liu, Monk:
> You get entity from "amd_sched_select_entity", and after that the spinlock of RQ backing this entity is also unlocked,
>
> But immediately you call "sched_job = amd_sched_entity_peek_job(entity)", keep in mind that this point the "entity" may
> Already be a wild pointer, since above "sched_select_entity' unlock the RQ's spinlock
>
> For gpu reset feature, it's more complicated, because in run_job() routine we need check entity's guilty pointer, but that time
> The entity from sched_job->s_entity may also already a wild pointer
>
>
> Hah, headache
>
> BR Monk
>
> -----Original Message-----
> From: Koenig, Christian
> Sent: 2017å¹´10æ??24æ?¥ 18:13
> To: Liu, Monk <Monk.Liu at amd.com>; Zhou, David(ChunMing) <David1.Zhou at amd.com>; amd-gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amd/scheduler: fix one used-after-free case for job->s_entity
>
> I thought we had fixed that one as well.
>
> The entity isn't accessed any more after amd_sched_entity_pop_job().
>
> Regards,
> Christian.
>
> Am 24.10.2017 um 12:06 schrieb Liu, Monk:
>> Christian
>>
>> Actually there are more wild pointer issue for entity in scheduler's main routine ....
>>
>>
>> See the message I replied to David
>>
>> BR Monk
>>
>> -----Original Message-----
>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
>> Of Christian K?nig
>> Sent: 2017å¹´10æ??24æ?¥ 18:01
>> To: Zhou, David(ChunMing) <David1.Zhou at amd.com>;
>> amd-gfx at lists.freedesktop.org
>> Subject: Re: [PATCH] drm/amd/scheduler: fix one used-after-free case
>> for job->s_entity
>>
>> Andrey already submitted a fix for this a few days ago.
>>
>> Christian.
>>
>> Am 24.10.2017 um 11:55 schrieb Chunming Zhou:
>>> The s_entity presented process could already be closed when calling amdgpu_job_free_cb.
>>> the s_entity will be buggy pointer after it's freed. See below calltrace:
>>>
>>> [  355.616964]
>>> ==================================================================
>>> [  355.617191] BUG: KASAN: use-after-free in
>>> amdgpu_job_free_cb+0x2f/0xc0 [amdgpu] [  355.617197] Read of size 8
>>> at addr ffff88039d593c40 by task kworker/9:1/100
>>>
>>> [  355.617206] CPU: 9 PID: 100 Comm: kworker/9:1 Not tainted
>>> 4.13.0-custom #1 [  355.617208] Hardware name: Gigabyte Technology
>>> Co., Ltd. Default string/X99P-SLI-CF, BIOS F23 07/22/2016 [
>>> 355.617342] Workqueue: events amd_sched_job_finish [amdgpu] [  355.617344] Call Trace:
>>> [  355.617351]  dump_stack+0x63/0x8d
>>> [  355.617356]  print_address_description+0x70/0x290
>>> [  355.617474]  ? amdgpu_job_free_cb+0x2f/0xc0 [amdgpu] [
>>> 355.617477]
>>> kasan_report+0x265/0x350 [  355.617479]  __asan_load8+0x54/0x90 [
>>> 355.617603]  amdgpu_job_free_cb+0x2f/0xc0 [amdgpu] [  355.617721]
>>> amd_sched_job_finish+0x161/0x180 [amdgpu] [  355.617725]
>>> process_one_work+0x2ab/0x700 [  355.617727]  worker_thread+0x90/0x720
>>> [  355.617731]  kthread+0x18c/0x1e0 [  355.617732]  ?
>>> process_one_work+0x700/0x700 [  355.617735]  ?
>>> kthread_create_on_node+0xb0/0xb0 [  355.617738]
>>> ret_from_fork+0x25/0x30
>>>
>>> [  355.617742] Allocated by task 1347:
>>> [  355.617747]  save_stack_trace+0x1b/0x20 [  355.617749]
>>> save_stack+0x46/0xd0 [  355.617751]  kasan_kmalloc+0xad/0xe0 [
>>> 355.617753]  kmem_cache_alloc_trace+0xef/0x200 [  355.617853]
>>> amdgpu_driver_open_kms+0x98/0x290 [amdgpu] [  355.617883]
>>> drm_open+0x38c/0x6e0 [drm] [  355.617908]  drm_stub_open+0x144/0x1b0
>>> [drm] [  355.617911]  chrdev_open+0x180/0x320 [  355.617913]
>>> do_dentry_open+0x3a2/0x570 [  355.617915]  vfs_open+0x86/0xe0 [
>>> 355.617918]  path_openat+0x49e/0x1db0 [  355.617919]
>>> do_filp_open+0x11c/0x1a0 [  355.617921]  do_sys_open+0x16f/0x2a0 [
>>> 355.617923]  SyS_open+0x1e/0x20 [  355.617926]
>>> do_syscall_64+0xea/0x210 [  355.617928]
>>> return_from_SYSCALL_64+0x0/0x6a
>>>
>>> [  355.617931] Freed by task 1347:
>>> [  355.617934]  save_stack_trace+0x1b/0x20 [  355.617936]
>>> save_stack+0x46/0xd0 [  355.617937]  kasan_slab_free+0x70/0xc0 [
>>> 355.617939]  kfree+0x9d/0x1c0 [  355.618038]
>>> amdgpu_driver_postclose_kms+0x1bc/0x3e0 [amdgpu] [  355.618063]
>>> drm_release+0x454/0x610 [drm] [  355.618065]  __fput+0x177/0x350 [
>>> 355.618066]  ____fput+0xe/0x10 [  355.618068]
>>> task_work_run+0xa0/0xc0 [  355.618070]  do_exit+0x456/0x1320 [
>>> 355.618072]
>>> do_group_exit+0x86/0x130 [  355.618074]  SyS_exit_group+0x1d/0x20 [
>>> 355.618076]  do_syscall_64+0xea/0x210 [  355.618078]
>>> return_from_SYSCALL_64+0x0/0x6a
>>>
>>> [  355.618081] The buggy address belongs to the object at ffff88039d593b80
>>>                    which belongs to the cache kmalloc-2048 of size
>>> 2048 [  355.618085] The buggy address is located 192 bytes inside of
>>>                    2048-byte region [ffff88039d593b80,
>>> ffff88039d594380) [  355.618087] The buggy address belongs to the page:
>>> [  355.618091] page:ffffea000e756400 count:1 mapcount:0 mapping:          (null) index:0x0 compound_mapcount: 0
>>> [  355.618095] flags: 0x2ffff0000008100(slab|head) [  355.618099] raw:
>>> 02ffff0000008100 0000000000000000 0000000000000000 00000001000f000f [
>>> 355.618103] raw: ffffea000edb0600 0000000200000002 ffff8803bfc0ea00
>>> 0000000000000000 [  355.618105] page dumped because: kasan: bad
>>> access detected
>>>
>>> [  355.618108] Memory state around the buggy address:
>>> [  355.618110]  ffff88039d593b00: fc fc fc fc fc fc fc fc fc fc fc fc
>>> fc fc fc fc [  355.618113]  ffff88039d593b80: fb fb fb fb fb fb fb fb
>>> fb fb fb fb fb fb fb fb [  355.618116] >ffff88039d593c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> [  355.618117]                                            ^
>>> [  355.618120]  ffff88039d593c80: fb fb fb fb fb fb fb fb fb fb fb fb
>>> fb fb fb fb [  355.618122]  ffff88039d593d00: fb fb fb fb fb fb fb fb
>>> fb fb fb fb fb fb fb fb [  355.618124]
>>> ==================================================================
>>> [  355.618126] Disabling lock debugging due to kernel taint
>>>
>>> Change-Id: I8ff7122796b8cd16fc26e9c40e8d4c8153d67e0c
>>> Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
>>> ---
>>>     drivers/gpu/drm/amd/scheduler/gpu_scheduler.c |  1 +
>>>     drivers/gpu/drm/amd/scheduler/gpu_scheduler.h | 27 ++++++++++++++-------------
>>>     2 files changed, 15 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>> b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>> index 007fdbd..8101ed7 100644
>>> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.c
>>> @@ -535,6 +535,7 @@ int amd_sched_job_init(struct amd_sched_job *job,
>>>     	if (!job->s_fence)
>>>     		return -ENOMEM;
>>>     	job->id = atomic64_inc_return(&sched->job_id_count);
>>> +	job->priority = job->s_entity->rq - job->sched->sched_rq;
>>>     
>>>     	INIT_WORK(&job->finish_work, amd_sched_job_finish);
>>>     	INIT_LIST_HEAD(&job->node);
>>> diff --git a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>> b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>> index e21299c..8808eb1 100644
>>> --- a/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>> +++ b/drivers/gpu/drm/amd/scheduler/gpu_scheduler.h
>>> @@ -77,6 +77,18 @@ struct amd_sched_fence {
>>>     	void                            *owner;
>>>     };
>>>     
>>> +enum amd_sched_priority {
>>> +	AMD_SCHED_PRIORITY_MIN,
>>> +	AMD_SCHED_PRIORITY_LOW = AMD_SCHED_PRIORITY_MIN,
>>> +	AMD_SCHED_PRIORITY_NORMAL,
>>> +	AMD_SCHED_PRIORITY_HIGH_SW,
>>> +	AMD_SCHED_PRIORITY_HIGH_HW,
>>> +	AMD_SCHED_PRIORITY_KERNEL,
>>> +	AMD_SCHED_PRIORITY_MAX,
>>> +	AMD_SCHED_PRIORITY_INVALID = -1,
>>> +	AMD_SCHED_PRIORITY_UNSET = -2
>>> +};
>>> +
>>>     struct amd_sched_job {
>>>     	struct amd_gpu_scheduler        *sched;
>>>     	struct amd_sched_entity         *s_entity;
>>> @@ -87,6 +99,7 @@ struct amd_sched_job {
>>>     	struct delayed_work		work_tdr;
>>>     	uint64_t			id;
>>>     	atomic_t karma;
>>> +	enum amd_sched_priority		priority;
>>>     };
>>>     
>>>     extern const struct dma_fence_ops amd_sched_fence_ops_scheduled;
>>> @@
>>> -118,18 +131,6 @@ struct amd_sched_backend_ops {
>>>     	void (*free_job)(struct amd_sched_job *sched_job);
>>>     };
>>>     
>>> -enum amd_sched_priority {
>>> -	AMD_SCHED_PRIORITY_MIN,
>>> -	AMD_SCHED_PRIORITY_LOW = AMD_SCHED_PRIORITY_MIN,
>>> -	AMD_SCHED_PRIORITY_NORMAL,
>>> -	AMD_SCHED_PRIORITY_HIGH_SW,
>>> -	AMD_SCHED_PRIORITY_HIGH_HW,
>>> -	AMD_SCHED_PRIORITY_KERNEL,
>>> -	AMD_SCHED_PRIORITY_MAX,
>>> -	AMD_SCHED_PRIORITY_INVALID = -1,
>>> -	AMD_SCHED_PRIORITY_UNSET = -2
>>> -};
>>> -
>>>     /**
>>>      * One scheduler is implemented for each hardware ring
>>>     */
>>> @@ -183,7 +184,7 @@ void amd_sched_job_kickout(struct amd_sched_job *s_job);
>>>     static inline enum amd_sched_priority
>>>     amd_sched_get_job_priority(struct amd_sched_job *job)
>>>     {
>>> -	return (job->s_entity->rq - job->sched->sched_rq);
>>> +	return job->priority;
>>>     }
>>>     
>>>     #endif
>> _______________________________________________
>> amd-gfx mailing list
>> amd-gfx at lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/amd-gfx
>



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