From: Lucas De Marchi <lucas.demarchi@intel.com>
To: Nirmoy Das <nirmoy.das@linux.intel.com>
Cc: "Shuicheng Lin" <shuicheng.lin@intel.com>,
intel-xe@lists.freedesktop.org,
"Matthew Brost" <matthew.brost@intel.com>,
"Thomas Hellstrom" <thomas.hellstrom@intel.com>,
dri-devel@lists.freedesktop.org,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH] drm/xe: Fix UBSAN shift-out-of-bounds failure
Date: Tue, 7 May 2024 08:18:18 -0500 [thread overview]
Message-ID: <fs2aq6wgrsoilkk4spw7fbmvxnbovn555qbney6aqwetflvg75@q4zsc2l2v64s> (raw)
In-Reply-To: <96b6a562-eeaf-49f9-9ade-d58fb061086d@linux.intel.com>
+Thomas, +Christian, +dri-devel
On Tue, May 07, 2024 at 11:42:46AM GMT, Nirmoy Das wrote:
>
>On 5/7/2024 11:39 AM, Nirmoy Das wrote:
>>
>>
>>On 5/7/2024 10:04 AM, Shuicheng Lin wrote:
>>>Here is the failure stack:
>>>[ 12.988209] ------------[ cut here ]------------
>>>[ 12.988216] UBSAN: shift-out-of-bounds in ./include/linux/log2.h:57:13
>>>[ 12.988232] shift exponent 64 is too large for 64-bit type 'long unsigned int'
>>>[ 12.988235] CPU: 4 PID: 1310 Comm: gnome-shell Tainted: G U 6.9.0-rc6+prerelease1158+ #19
>>>[ 12.988237] Hardware name: Intel Corporation Raptor Lake Client Platform/RPL-S ADP-S DDR5 UDIMM CRB, BIOS RPLSFWI1.R00.3301.A02.2208050712 08/05/2022
>>>[ 12.988239] Call Trace:
>>>[ 12.988240] <TASK>
>>>[ 12.988242] dump_stack_lvl+0xd7/0xf0
>>>[ 12.988248] dump_stack+0x10/0x20
>>>[ 12.988250] ubsan_epilogue+0x9/0x40
>>>[ 12.988253] __ubsan_handle_shift_out_of_bounds+0x10e/0x170
>>>[ 12.988260] dma_resv_reserve_fences.cold+0x2b/0x48
>>>[ 12.988262] ? ww_mutex_lock_interruptible+0x3c/0x110
>>>[ 12.988267] drm_exec_prepare_obj+0x45/0x60 [drm_exec]
>>>[ 12.988271] ? vm_bind_ioctl_ops_execute+0x5b/0x740 [xe]
>>>[ 12.988345] vm_bind_ioctl_ops_execute+0x78/0x740 [xe]
>>>
>>>It is caused by the value 0 of parameter num_fences in function drm_exec_prepare_obj.
>>>And lead to in function __rounddown_pow_of_two, "0 - 1" causes the shift-out-of-bounds.
>>>For the num_fences, it should be 1 at least.
>>>
>>>Cc: Matthew Brost<matthew.brost@intel.com>
>>>Signed-off-by: Shuicheng Lin<shuicheng.lin@intel.com>
>>>---
>>> drivers/gpu/drm/xe/xe_vm.c | 4 ++--
>>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>>diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
>>>index d17192c8b7de..96cb4d9762a3 100644
>>>--- a/drivers/gpu/drm/xe/xe_vm.c
>>>+++ b/drivers/gpu/drm/xe/xe_vm.c
>>>@@ -2692,7 +2692,7 @@ static int vma_lock_and_validate(struct drm_exec *exec, struct xe_vma *vma,
>>> if (bo) {
>>> if (!bo->vm)
>>>- err = drm_exec_prepare_obj(exec, &bo->ttm.base, 0);
>>>+ err = drm_exec_prepare_obj(exec, &bo->ttm.base, 1);
>>
>>This needs to be fixed in drm_exec_prepare_obj() by checking
>>num_fences and not calling dma_resv_reserve_fences()
>>
>or just call drm_exec_lock_obj() here. ref:
>https://patchwork.freedesktop.org/patch/577487/
we are hit again by this. Couldn't we change drm_exec_prepare_obj() to
check num_fences and if is 0 just fallback to just do
drm_exec_lock_obj() as "the least amount of work needed in this case"?
Something like this:
| diff --git a/drivers/gpu/drm/drm_exec.c b/drivers/gpu/drm/drm_exec.c
| index 2da094bdf8a4..68b5f6210b09 100644
| --- a/drivers/gpu/drm/drm_exec.c
| +++ b/drivers/gpu/drm/drm_exec.c
| @@ -296,10 +296,12 @@ int drm_exec_prepare_obj(struct drm_exec *exec, struct drm_gem_object *obj,
| if (ret)
| return ret;
|
| - ret = dma_resv_reserve_fences(obj->resv, num_fences);
| - if (ret) {
| - drm_exec_unlock_obj(exec, obj);
| - return ret;
| + if (num_fences) {
| + ret = dma_resv_reserve_fences(obj->resv, num_fences);
| + if (ret) {
| + drm_exec_unlock_obj(exec, obj);
| + return ret;
| + }
| }
|
| return 0;
thanks
Lucas De Marchi
>
>Nirmoy
>
>>
>>Regards,
>>
>>Nirmoy
>>
>>> if (!err && validate)
>>> err = xe_bo_validate(bo, xe_vma_vm(vma), true);
>>> }
>>>@@ -2777,7 +2777,7 @@ static int vm_bind_ioctl_ops_lock_and_prep(struct drm_exec *exec,
>>> struct xe_vma_op *op;
>>> int err;
>>>- err = drm_exec_prepare_obj(exec, xe_vm_obj(vm), 0);
>>>+ err = drm_exec_prepare_obj(exec, xe_vm_obj(vm), 1);
>>> if (err)
>>> return err;
next parent reply other threads:[~2024-05-07 13:18 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20240507080456.613786-1-shuicheng.lin@intel.com>
[not found] ` <2a9a7bb2-c74d-44fb-b9d2-cbb42e462d0f@linux.intel.com>
[not found] ` <96b6a562-eeaf-49f9-9ade-d58fb061086d@linux.intel.com>
2024-05-07 13:18 ` Lucas De Marchi [this message]
2024-05-07 13:23 ` [PATCH] drm/xe: Fix UBSAN shift-out-of-bounds failure Christian König
[not found] ` <20240507130411.630361-1-shuicheng.lin@intel.com>
2024-05-09 3:38 ` Lucas De Marchi
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