Am 19.12.24 um 11:38 schrieb Arunpravin Paneer Selvam:
Fix out-of-bounds issue in userq fence create when
accessing the userq xa structure. Added a lock to
protect the race condition.

v2:(Christian)
   - Acquire xa lock only for the xa_for_each blocks and
     not for the kvmalloc_array() memory allocation part.

v3:
   - Replacing the kvmalloc_array() storage with xa_alloc()
     solves the problem.

BUG: KASAN: slab-out-of-bounds in amdgpu_userq_fence_create+0x726/0x880 [amdgpu]
[  +0.000006] Call Trace:
[  +0.000005]  <TASK>
[  +0.000005]  dump_stack_lvl+0x6c/0x90
[  +0.000011]  print_report+0xc4/0x5e0
[  +0.000009]  ? srso_return_thunk+0x5/0x5f
[  +0.000008]  ? kasan_complete_mode_report_info+0x26/0x1d0
[  +0.000007]  ? amdgpu_userq_fence_create+0x726/0x880 [amdgpu]
[  +0.000405]  kasan_report+0xdf/0x120
[  +0.000009]  ? amdgpu_userq_fence_create+0x726/0x880 [amdgpu]
[  +0.000405]  __asan_report_store8_noabort+0x17/0x20
[  +0.000007]  amdgpu_userq_fence_create+0x726/0x880 [amdgpu]
[  +0.000406]  ? __pfx_amdgpu_userq_fence_create+0x10/0x10 [amdgpu]
[  +0.000408]  ? srso_return_thunk+0x5/0x5f
[  +0.000008]  ? ttm_resource_move_to_lru_tail+0x235/0x4f0 [ttm]
[  +0.000013]  ? srso_return_thunk+0x5/0x5f
[  +0.000008]  amdgpu_userq_signal_ioctl+0xd29/0x1c70 [amdgpu]
[  +0.000412]  ? __pfx_amdgpu_userq_signal_ioctl+0x10/0x10 [amdgpu]
[  +0.000404]  ? try_to_wake_up+0x165/0x1840
[  +0.000010]  ? __pfx_futex_wake_mark+0x10/0x10
[  +0.000011]  drm_ioctl_kernel+0x178/0x2f0 [drm]
[  +0.000050]  ? __pfx_amdgpu_userq_signal_ioctl+0x10/0x10 [amdgpu]
[  +0.000404]  ? __pfx_drm_ioctl_kernel+0x10/0x10 [drm]
[  +0.000043]  ? __kasan_check_read+0x11/0x20
[  +0.000007]  ? srso_return_thunk+0x5/0x5f
[  +0.000007]  ? __kasan_check_write+0x14/0x20
[  +0.000008]  drm_ioctl+0x513/0xd20 [drm]
[  +0.000040]  ? __pfx_amdgpu_userq_signal_ioctl+0x10/0x10 [amdgpu]
[  +0.000407]  ? __pfx_drm_ioctl+0x10/0x10 [drm]
[  +0.000044]  ? srso_return_thunk+0x5/0x5f
[  +0.000007]  ? _raw_spin_lock_irqsave+0x99/0x100
[  +0.000007]  ? __pfx__raw_spin_lock_irqsave+0x10/0x10
[  +0.000006]  ? __rseq_handle_notify_resume+0x188/0xc30
[  +0.000008]  ? srso_return_thunk+0x5/0x5f
[  +0.000008]  ? srso_return_thunk+0x5/0x5f
[  +0.000006]  ? _raw_spin_unlock_irqrestore+0x27/0x50
[  +0.000010]  amdgpu_drm_ioctl+0xcd/0x1d0 [amdgpu]
[  +0.000388]  __x64_sys_ioctl+0x135/0x1b0
[  +0.000009]  x64_sys_call+0x1205/0x20d0
[  +0.000007]  do_syscall_64+0x4d/0x120
[  +0.000008]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  +0.000007] RIP: 0033:0x7f7c3d31a94f

Signed-off-by: Arunpravin Paneer Selvam <arunpravin.paneersel...@amd.com>
---
  .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.c   | 43 +++++++------------
  .../gpu/drm/amd/amdgpu/amdgpu_userq_fence.h   |  3 +-
  2 files changed, 17 insertions(+), 29 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c 
b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
index 2e7271362ace..4289bed6c1f7 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.c
@@ -122,10 +122,11 @@ int amdgpu_userq_fence_driver_alloc(struct amdgpu_device 
*adev,
void amdgpu_userq_fence_driver_process(struct amdgpu_userq_fence_driver *fence_drv)
  {
+       struct amdgpu_userq_fence_driver *stored_fence_drv;
        struct amdgpu_userq_fence *userq_fence, *tmp;
        struct dma_fence *fence;
+       unsigned long index;
        u64 rptr;
-       int i;
if (!fence_drv)
                return;
@@ -141,8 +142,8 @@ void amdgpu_userq_fence_driver_process(struct 
amdgpu_userq_fence_driver *fence_d
dma_fence_signal(fence); - for (i = 0; i < userq_fence->fence_drv_array_count; i++)
-                       
amdgpu_userq_fence_driver_put(userq_fence->fence_drv_array[i]);
+               xa_for_each(&userq_fence->fence_drv_xa, index, stored_fence_drv)
+                       amdgpu_userq_fence_driver_put(stored_fence_drv);
list_del(&userq_fence->link);
                dma_fence_put(fence);
@@ -221,34 +222,24 @@ int amdgpu_userq_fence_create(struct 
amdgpu_usermode_queue *userq,
        dma_fence_init(fence, &amdgpu_userq_fence_ops, &userq_fence->lock,
                       fence_drv->context, seq);
+ xa_init_flags(&userq_fence->fence_drv_xa, XA_FLAGS_ALLOC);
+
        amdgpu_userq_fence_driver_get(fence_drv);
        dma_fence_get(fence);
if (!xa_empty(&userq->fence_drv_xa)) {
                struct amdgpu_userq_fence_driver *stored_fence_drv;
-               unsigned long index, count = 0;
-               int i = 0;
-
-               xa_for_each(&userq->fence_drv_xa, index, stored_fence_drv)
-                       count++;
-
-               userq_fence->fence_drv_array =
-                       kvmalloc_array(count,
-                                      sizeof(struct amdgpu_userq_fence_driver 
*),
-                                      GFP_KERNEL);
-
-               if (userq_fence->fence_drv_array) {
-                       xa_for_each(&userq->fence_drv_xa, index, 
stored_fence_drv) {
-                               userq_fence->fence_drv_array[i] = 
stored_fence_drv;
-                               xa_erase(&userq->fence_drv_xa, index);
-                               i++;
-                       }
+               unsigned long index_uq;
+               u32 index_uf;
+               int err;
+
+               xa_for_each(&userq->fence_drv_xa, index_uq, stored_fence_drv) {
+                       err = xa_alloc_irq(&userq_fence->fence_drv_xa, 
&index_uf,
+                                          stored_fence_drv, xa_limit_32b, 
GFP_KERNEL);

That is even worse than what was discussed before. Now you have two XAs and the second is incorrectly using GFP_KERNEL.

Regards,
Christian.

+                       if (err)
+                               return err;
                }
-
-               userq_fence->fence_drv_array_count = i;
-       } else {
-               userq_fence->fence_drv_array = NULL;
-               userq_fence->fence_drv_array_count = 0;
+               xa_destroy(&userq->fence_drv_xa);
        }
/* Check if hardware has already processed the job */
@@ -300,8 +291,6 @@ static void amdgpu_userq_fence_free(struct rcu_head *rcu)
/* Release the fence driver reference */
        amdgpu_userq_fence_driver_put(fence_drv);
-
-       kvfree(userq_fence->fence_drv_array);
        kmem_cache_free(amdgpu_userq_fence_slab, userq_fence);
  }
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h
index f1a90840ac1f..3283e5573d10 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_userq_fence.h
@@ -37,9 +37,8 @@ struct amdgpu_userq_fence {
         */
        spinlock_t lock;
        struct list_head link;
-       unsigned long fence_drv_array_count;
+       struct xarray fence_drv_xa;
        struct amdgpu_userq_fence_driver *fence_drv;
-       struct amdgpu_userq_fence_driver **fence_drv_array;
  };
struct amdgpu_userq_fence_driver {

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