diff mbox series

[v3] dma-buf: fix racing conflict of dma_heap_add()

Message ID TYCP286MB2323D71DEC1D008BEA6F7ABBCA399@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM
State New
Headers
Series [v3] dma-buf: fix racing conflict of dma_heap_add() |

Commit Message

Dawei Li Nov. 2, 2022, 3:58 p.m. UTC 
  Racing conflict could be:
task A                 task B
list_for_each_entry
strcmp(h->name))
                       list_for_each_entry
                       strcmp(h->name)
kzalloc                kzalloc
......                 .....
device_create          device_create
list_add
                       list_add

The root cause is that task B has no idea about the fact someone
else(A) has inserted heap with same name when it calls list_add,
so a potential collision occurs.

v1: https://lore.kernel.org/all/TYCP286MB2323950197F60FC3473123B7CA349@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM/

v1->v2: Narrow down locking scope, check the existence of heap before
insertion, as suggested by Andrew Davis.

v2->v3: Remove double checking.

Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")

base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7

Signed-off-by: Dawei Li <set_pte_at@outlook.com>
---
 drivers/dma-buf/dma-heap.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

Comments

T.J. Mercier Nov. 2, 2022, 4:54 p.m. UTC | #1 
On Wed, Nov 2, 2022 at 8:59 AM Dawei Li <set_pte_at@outlook.com> wrote:
>
> Racing conflict could be:
> task A                 task B
> list_for_each_entry
> strcmp(h->name))
>                        list_for_each_entry
>                        strcmp(h->name)
> kzalloc                kzalloc
> ......                 .....
> device_create          device_create
> list_add
>                        list_add
>
> The root cause is that task B has no idea about the fact someone
> else(A) has inserted heap with same name when it calls list_add,
> so a potential collision occurs.
>
> v1: https://lore.kernel.org/all/TYCP286MB2323950197F60FC3473123B7CA349@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM/
>
> v1->v2: Narrow down locking scope, check the existence of heap before
> insertion, as suggested by Andrew Davis.
>
> v2->v3: Remove double checking.
>
> Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")
>
> base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7
>
> Signed-off-by: Dawei Li <set_pte_at@outlook.com>
> ---
>  drivers/dma-buf/dma-heap.c | 29 +++++++++++++++--------------
>  1 file changed, 15 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
> index 8f5848aa144f..7a25e98259ea 100644
> --- a/drivers/dma-buf/dma-heap.c
> +++ b/drivers/dma-buf/dma-heap.c
> @@ -233,18 +233,6 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
>                 return ERR_PTR(-EINVAL);
>         }
>
> -       /* check the name is unique */
> -       mutex_lock(&heap_list_lock);
> -       list_for_each_entry(h, &heap_list, list) {
> -               if (!strcmp(h->name, exp_info->name)) {
> -                       mutex_unlock(&heap_list_lock);
> -                       pr_err("dma_heap: Already registered heap named %s\n",
> -                              exp_info->name);
> -                       return ERR_PTR(-EINVAL);
> -               }
> -       }
> -       mutex_unlock(&heap_list_lock);
> -
>         heap = kzalloc(sizeof(*heap), GFP_KERNEL);
>         if (!heap)
>                 return ERR_PTR(-ENOMEM);
> @@ -283,13 +271,26 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
>                 err_ret = ERR_CAST(dev_ret);
>                 goto err2;
>         }
> -       /* Add heap to the list */
> +
>         mutex_lock(&heap_list_lock);
> +       /* check the name is unique */
> +       list_for_each_entry(h, &heap_list, list) {
> +               if (!strcmp(h->name, exp_info->name)) {
> +                       mutex_unlock(&heap_list_lock);
> +                       pr_err("dma_heap: Already registered heap named %s\n",
> +                              exp_info->name);
> +                       err_ret = ERR_PTR(-EINVAL);
> +                       goto err3;
> +               }
> +       }
> +
> +       /* Add heap to the list */
>         list_add(&heap->list, &heap_list);
>         mutex_unlock(&heap_list_lock);
>
>         return heap;
> -
> +err3:
> +       device_destroy(dma_heap_class, heap->heap_devt);
>  err2:
>         cdev_del(&heap->heap_cdev);
>  err1:
> --
> 2.25.1
>

Reviewed-by: T.J. Mercier <tjmercier@google.com>

Thanks!
Andrew Davis Nov. 2, 2022, 5:13 p.m. UTC | #2 
On 11/2/22 10:58 AM, Dawei Li wrote:
> Racing conflict could be:
> task A                 task B
> list_for_each_entry
> strcmp(h->name))
>                         list_for_each_entry
>                         strcmp(h->name)
> kzalloc                kzalloc
> ......                 .....
> device_create          device_create
> list_add
>                         list_add
> 
> The root cause is that task B has no idea about the fact someone
> else(A) has inserted heap with same name when it calls list_add,
> so a potential collision occurs.
> 
> v1: https://lore.kernel.org/all/TYCP286MB2323950197F60FC3473123B7CA349@TYCP286MB2323.JPNP286.PROD.OUTLOOK.COM/
> 
> v1->v2: Narrow down locking scope, check the existence of heap before
> insertion, as suggested by Andrew Davis.
> 
> v2->v3: Remove double checking.

The above version info should be in a cover letter or below
the --- line so it doesn't end up in the commit message in tree.

> 
> Fixes: c02a81fba74f ("dma-buf: Add dma-buf heaps framework")
> 
> base-commit: 447fb14bf07905b880c9ed1ea92c53d6dd0649d7
> 

Same as above, plus this is an odd base, maybe just use "v6.1-rc2".

> Signed-off-by: Dawei Li <set_pte_at@outlook.com>
> ---
>   drivers/dma-buf/dma-heap.c | 29 +++++++++++++++--------------
>   1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
> index 8f5848aa144f..7a25e98259ea 100644
> --- a/drivers/dma-buf/dma-heap.c
> +++ b/drivers/dma-buf/dma-heap.c
> @@ -233,18 +233,6 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
>   		return ERR_PTR(-EINVAL);
>   	}
>   
> -	/* check the name is unique */
> -	mutex_lock(&heap_list_lock);
> -	list_for_each_entry(h, &heap_list, list) {
> -		if (!strcmp(h->name, exp_info->name)) {
> -			mutex_unlock(&heap_list_lock);
> -			pr_err("dma_heap: Already registered heap named %s\n",
> -			       exp_info->name);
> -			return ERR_PTR(-EINVAL);
> -		}
> -	}
> -	mutex_unlock(&heap_list_lock);
> -
>   	heap = kzalloc(sizeof(*heap), GFP_KERNEL);
>   	if (!heap)
>   		return ERR_PTR(-ENOMEM);
> @@ -283,13 +271,26 @@ struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
>   		err_ret = ERR_CAST(dev_ret);
>   		goto err2;
>   	}
> -	/* Add heap to the list */
> +
>   	mutex_lock(&heap_list_lock);
> +	/* check the name is unique */
> +	list_for_each_entry(h, &heap_list, list) {
> +		if (!strcmp(h->name, exp_info->name)) {
> +			mutex_unlock(&heap_list_lock);
> +			pr_err("dma_heap: Already registered heap named %s\n",
> +			       exp_info->name);
> +			err_ret = ERR_PTR(-EINVAL);
> +			goto err3;
> +		}
> +	}
> +
> +	/* Add heap to the list */
>   	list_add(&heap->list, &heap_list);
>   	mutex_unlock(&heap_list_lock);
>   
>   	return heap;
> -

Would like to keep this new line after the return statement.

Andrew

> +err3:
> +	device_destroy(dma_heap_class, heap->heap_devt);
>   err2:
>   	cdev_del(&heap->heap_cdev);
>   err1:
diff mbox series

Patch

diff --git a/drivers/dma-buf/dma-heap.c b/drivers/dma-buf/dma-heap.c
index 8f5848aa144f..7a25e98259ea 100644
--- a/drivers/dma-buf/dma-heap.c
+++ b/drivers/dma-buf/dma-heap.c
@@ -233,18 +233,6 @@  struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 		return ERR_PTR(-EINVAL);
 	}
 
-	/* check the name is unique */
-	mutex_lock(&heap_list_lock);
-	list_for_each_entry(h, &heap_list, list) {
-		if (!strcmp(h->name, exp_info->name)) {
-			mutex_unlock(&heap_list_lock);
-			pr_err("dma_heap: Already registered heap named %s\n",
-			       exp_info->name);
-			return ERR_PTR(-EINVAL);
-		}
-	}
-	mutex_unlock(&heap_list_lock);
-
 	heap = kzalloc(sizeof(*heap), GFP_KERNEL);
 	if (!heap)
 		return ERR_PTR(-ENOMEM);
@@ -283,13 +271,26 @@  struct dma_heap *dma_heap_add(const struct dma_heap_export_info *exp_info)
 		err_ret = ERR_CAST(dev_ret);
 		goto err2;
 	}
-	/* Add heap to the list */
+
 	mutex_lock(&heap_list_lock);
+	/* check the name is unique */
+	list_for_each_entry(h, &heap_list, list) {
+		if (!strcmp(h->name, exp_info->name)) {
+			mutex_unlock(&heap_list_lock);
+			pr_err("dma_heap: Already registered heap named %s\n",
+			       exp_info->name);
+			err_ret = ERR_PTR(-EINVAL);
+			goto err3;
+		}
+	}
+
+	/* Add heap to the list */
 	list_add(&heap->list, &heap_list);
 	mutex_unlock(&heap_list_lock);
 
 	return heap;
-
+err3:
+	device_destroy(dma_heap_class, heap->heap_devt);
 err2:
 	cdev_del(&heap->heap_cdev);
 err1: