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

[Christian König]

Sorry for the vacation and sick leave induced delay.

I've just pushed this to drm-misc-fixes.

Thanks,
Christian.

Am 24.06.21 um 21:43 schrieb Jason Ekstrand:
> I don't have drm-misc access.  Mind pushing?
>
> On Thu, Jun 24, 2021 at 12:59 PM Christian König
> <christian.koenig at amd.com> wrote:
>> 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 at jlekstrand.net>
>>> Fixes: a02b9dc90d84 ("dma-buf/sync_file: refactor fence storage in struct sync_file")
>>> Cc: Gustavo Padovan <gustavo.padovan at collabora.co.uk>
>>> Cc: Christian König <christian.koenig at amd.com>
>> Reviewed-by: Christian König <christian.koenig at amd.com>
>>
>>> ---
>>>    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;
>>>