[PATCH] dma-buf/dma-resv: Stop leaking on krealloc() failure

[Christian König]

Am 13.07.23 um 21:47 schrieb Ville Syrjala:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
>
> Currently dma_resv_get_fences() will leak the previously
> allocated array if the fence iteration got restarted and
> the krealloc_array() fails.
>
> Free the old array by hand, and make sure we still clear
> the returned *fences so the caller won't end up accessing
> freed memory. Some (but not all) of the callers of
> dma_resv_get_fences() seem to still trawl through the
> array even when dma_resv_get_fences() failed. And let's
> zero out *num_fences as well for good measure.
>
> Cc: Sumit Semwal <sumit.semwal at linaro.org>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: linux-media at vger.kernel.org
> Cc: dri-devel at lists.freedesktop.org
> Cc: linaro-mm-sig at lists.linaro.org
> Fixes: d3c80698c9f5 ("dma-buf: use new iterator in dma_resv_get_fences v3")
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

Good catch, Reviewed-by: Christian König <christian.koenig at amd.com>

Should I add a CC: stable and push to drm-misc-fixes?

Thanks,
Christian.

> ---
>   drivers/dma-buf/dma-resv.c | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
> index b6f71eb00866..38b4110378de 100644
> --- a/drivers/dma-buf/dma-resv.c
> +++ b/drivers/dma-buf/dma-resv.c
> @@ -571,6 +571,7 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
>   	dma_resv_for_each_fence_unlocked(&cursor, fence) {
>   
>   		if (dma_resv_iter_is_restarted(&cursor)) {
> +			struct dma_fence **new_fences;
>   			unsigned int count;
>   
>   			while (*num_fences)
> @@ -579,13 +580,17 @@ int dma_resv_get_fences(struct dma_resv *obj, enum dma_resv_usage usage,
>   			count = cursor.num_fences + 1;
>   
>   			/* Eventually re-allocate the array */
> -			*fences = krealloc_array(*fences, count,
> -						 sizeof(void *),
> -						 GFP_KERNEL);
> -			if (count && !*fences) {
> +			new_fences = krealloc_array(*fences, count,
> +						    sizeof(void *),
> +						    GFP_KERNEL);
> +			if (count && !new_fences) {
> +				kfree(*fences);
> +				*fences = NULL;
> +				*num_fences = 0;
>   				dma_resv_iter_end(&cursor);
>   				return -ENOMEM;
>   			}
> +			*fences = new_fences;
>   		}
>   
>   		(*fences)[(*num_fences)++] = dma_fence_get(fence);