Re: [PATCH] dma-buf/sync_file: Don't leak fences on merge failure

[Christian König <christian.koenig@xxxxxxx>]

Am 24.06.21 um 19:47 schrieb Jason Ekstrand:
> Each add_fence() call does a dma_fence_get() on the relevant fence.  In
> the error path, we weren't calling dma_fence_put() so all those fences
> got leaked.  Also, in the krealloc_array failure case, we weren't
> freeing the fences array.  Instead, ensure that i and fences are always
> zero-initialized and dma_fence_put() all the fences and kfree(fences) on
> every error path.
>
> Signed-off-by: Jason Ekstrand <jason@xxxxxxxxxxxxxx>
> Fixes: a02b9dc90d84 ("dma-buf/sync_file: refactor fence storage in struct sync_file")
> Cc: Gustavo Padovan <gustavo.padovan@xxxxxxxxxxxxxxx>
> Cc: Christian König <christian.koenig@xxxxxxx>

Reviewed-by: Christian König <christian.koenig@xxxxxxx>

> ---
>   drivers/dma-buf/sync_file.c | 13 +++++++------
>   1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma-buf/sync_file.c b/drivers/dma-buf/sync_file.c
> index 20d9bddbb985b..394e6e1e96860 100644
> --- a/drivers/dma-buf/sync_file.c
> +++ b/drivers/dma-buf/sync_file.c
> @@ -211,8 +211,8 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>   					 struct sync_file *b)
>   {
>   	struct sync_file *sync_file;
> -	struct dma_fence **fences, **nfences, **a_fences, **b_fences;
> -	int i, i_a, i_b, num_fences, a_num_fences, b_num_fences;
> +	struct dma_fence **fences = NULL, **nfences, **a_fences, **b_fences;
> +	int i = 0, i_a, i_b, num_fences, a_num_fences, b_num_fences;
>   
>   	sync_file = sync_file_alloc();
>   	if (!sync_file)
> @@ -236,7 +236,7 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>   	 * If a sync_file can only be created with sync_file_merge
>   	 * and sync_file_create, this is a reasonable assumption.
>   	 */
> -	for (i = i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
> +	for (i_a = i_b = 0; i_a < a_num_fences && i_b < b_num_fences; ) {
>   		struct dma_fence *pt_a = a_fences[i_a];
>   		struct dma_fence *pt_b = b_fences[i_b];
>   
> @@ -277,15 +277,16 @@ static struct sync_file *sync_file_merge(const char *name, struct sync_file *a,
>   		fences = nfences;
>   	}
>   
> -	if (sync_file_set_fence(sync_file, fences, i) < 0) {
> -		kfree(fences);
> +	if (sync_file_set_fence(sync_file, fences, i) < 0)
>   		goto err;
> -	}
>   
>   	strlcpy(sync_file->user_name, name, sizeof(sync_file->user_name));
>   	return sync_file;
>   
>   err:
> +	while (i)
> +		dma_fence_put(fences[--i]);
> +	kfree(fences);
>   	fput(sync_file->file);
>   	return NULL;
>