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

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@linaro.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Cc: linaro-mm-sig@lists.linaro.org
Fixes: d3c80698c9f5 ("dma-buf: use new iterator in dma_resv_get_fences v3")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20230713194745.1751-1-ville.syrjala@linux.intel.com
Signed-off-by: Christian König <christian.koenig@amd.com>

diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c
index b6f71eb..38b4110 100644 (file)
--- 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);