[FFmpeg-cvslog] avfilter/vf_dnn_detect: Fix null pointer dereference

[Zhao Zhili]

ffmpeg | branch: master | Zhao Zhili <zhilizhao at tencent.com> | Wed May  8 00:08:18 2024 +0800| [553c572204392f7a74bbfebcf3d33f1161976c8b] | committer: Guo Yejun

avfilter/vf_dnn_detect: Fix null pointer dereference

Signed-off-by: Zhao Zhili <zhilizhao at tencent.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=553c572204392f7a74bbfebcf3d33f1161976c8b
---

 libavfilter/vf_dnn_detect.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libavfilter/vf_dnn_detect.c b/libavfilter/vf_dnn_detect.c
index 926966368a..1830bae181 100644
--- a/libavfilter/vf_dnn_detect.c
+++ b/libavfilter/vf_dnn_detect.c
@@ -807,11 +807,13 @@ static av_cold void dnn_detect_uninit(AVFilterContext *context)
     DnnDetectContext *ctx = context->priv;
     AVDetectionBBox *bbox;
     ff_dnn_uninit(&ctx->dnnctx);
-    while(av_fifo_can_read(ctx->bboxes_fifo)) {
-        av_fifo_read(ctx->bboxes_fifo, &bbox, 1);
-        av_freep(&bbox);
+    if (ctx->bboxes_fifo) {
+        while (av_fifo_can_read(ctx->bboxes_fifo)) {
+            av_fifo_read(ctx->bboxes_fifo, &bbox, 1);
+            av_freep(&bbox);
+        }
+        av_fifo_freep2(&ctx->bboxes_fifo);
     }
-    av_fifo_freep2(&ctx->bboxes_fifo);
     av_freep(&ctx->anchors);
     free_detect_labels(ctx);
 }