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

[Jason Ekstrand]

No worries.  Thanks for pushing!

On Mon, Jul 12, 2021 at 6:37 AM Christian König
<christian.koenig at amd.com> wrote:
>
> 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;
> >>>
>