[Mesa-dev] [PATCH v2] virgl: Use right key to insert resource to hash.

[Lepton Wu]

On Mon, Apr 8, 2019 at 11:10 AM Chia-I Wu <olvaffe at gmail.com> wrote:
>
>
>
> On Mon, Apr 8, 2019 at 9:34 AM Lepton Wu <lepton at chromium.org> wrote:
>>
>> The old code could use gem name as key when inserting it to bo_handles
>> hash table while trying to remove it from hash table with bo_handle as
>> key in virgl_hw_res_destroy and then it fail to remove it from bo_handles
>> hash table. This triggers use after free. Also, we should insert resource
>> to bo_names hash table when handle type is SHARED.
>>
>> Signed-off-by: Lepton Wu <lepton at chromium.org>
>> ---
>>  .../winsys/virgl/drm/virgl_drm_winsys.c       | 24 +++++++++++++------
>>  1 file changed, 17 insertions(+), 7 deletions(-)
>>
>> diff --git a/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c b/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
>> index 2cf8b4ba076..af92b6a98fc 100644
>> --- a/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
>> +++ b/src/gallium/winsys/virgl/drm/virgl_drm_winsys.c
>> @@ -406,6 +406,12 @@ virgl_drm_winsys_resource_create_handle(struct virgl_winsys *qws,
>>        return NULL;
>>     }
>>
>> +   if (whandle->type != WINSYS_HANDLE_TYPE_FD &&
>> +       whandle->type != WINSYS_HANDLE_TYPE_SHARED) {
>> +      fprintf(stderr, "Unexpected handle type: %d\n", whandle->type);
>> +      return NULL;
>> +   }
>> +
>>     mtx_lock(&qdws->bo_handles_mutex);
>>
>>     if (whandle->type == WINSYS_HANDLE_TYPE_SHARED) {
>> @@ -424,13 +430,13 @@ virgl_drm_winsys_resource_create_handle(struct virgl_winsys *qws,
>>           res = NULL;
>>           goto done;
>>        }
>> -   }
>>
>> -   res = util_hash_table_get(qdws->bo_handles, (void*)(uintptr_t)handle);
>> -   if (res) {
>> -      struct virgl_hw_res *r = NULL;
>> -      virgl_drm_resource_reference(qdws, &r, res);
>> -      goto done;
>> +      res = util_hash_table_get(qdws->bo_handles, (void*)(uintptr_t)handle);
>> +      if (res) {
>> +         struct virgl_hw_res *r = NULL;
>> +         virgl_drm_resource_reference(qdws, &r, res);
>> +         goto done;
>> +      }
>>     }
>>
> You can still run into troubles when asked to import a buffer by both its prime fd and its flink name.
But it seems there is no way to fix it at user space, right? Every
time we got a flink name for
the first time, kernel will give a new handle and no way to  reuse any
res from hash table.
>
>>     res = CALLOC_STRUCT(virgl_hw_res);
>> @@ -448,6 +454,8 @@ virgl_drm_winsys_resource_create_handle(struct virgl_winsys *qws,
>>           goto done;
>>        }
>>        res->bo_handle = open_arg.handle;
>> +      res->flinked = true;
>> +      res->flink = whandle->handle;
>>     }
>>     res->name = handle;
>
> res->name has no user.  Remove it.
>
> It is also less confusing to make sure `handle' means GEM handle at this point, by calling either GEM_OPEN or drmPrimeFDToHandle depending on the handle type.
>
>>
>> @@ -469,7 +477,9 @@ virgl_drm_winsys_resource_create_handle(struct virgl_winsys *qws,
>>     res->num_cs_references = 0;
>>     res->fence_fd = -1;
>>
>> -   util_hash_table_set(qdws->bo_handles, (void *)(uintptr_t)handle, res);
>> +   util_hash_table_set(qdws->bo_handles, (void *)(uintptr_t)res->bo_handle, res);
>> +   if (whandle->type == WINSYS_HANDLE_TYPE_SHARED)
>> +      util_hash_table_set(qdws->bo_names, (void *)(uintptr_t)res->flink, res);
>>
>>  done:
>>     mtx_unlock(&qdws->bo_handles_mutex);
>> --
>> 2.21.0.392.gf8f6787159e-goog
>>