From faedf9f8ef5b657064ecf6af8d1ba767ada60bf4 Mon Sep 17 00:00:00 2001
From: happyworker <208suo@208suo.com>
Date: Tue, 25 Jun 2024 10:58:39 +0800
Subject: [PATCH] fix-CVE-2023-51798

---
 libavfilter/vf_minterpolate.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/libavfilter/vf_minterpolate.c b/libavfilter/vf_minterpolate.c
index b0bb238..745987c 100644
--- a/libavfilter/vf_minterpolate.c
+++ b/libavfilter/vf_minterpolate.c
@@ -1086,9 +1086,13 @@ static void interpolate(AVFilterLink *inlink, AVFrame *avf_out)
     pts = av_rescale(avf_out->pts, (int64_t) ALPHA_MAX * outlink->time_base.num * inlink->time_base.den,
                                    (int64_t)             outlink->time_base.den * inlink->time_base.num);
 
-    alpha = (pts - mi_ctx->frames[1].avf->pts * ALPHA_MAX) / (mi_ctx->frames[2].avf->pts - mi_ctx->frames[1].avf->pts);
-    alpha = av_clip(alpha, 0, ALPHA_MAX);
-
+    if (mi_ctx->frames[2].avf->pts > mi_ctx->frames[1].avf->pts) {
+        alpha = (pts - mi_ctx->frames[1].avf->pts * ALPHA_MAX) / (mi_ctx->frames[2].avf->pts - mi_ctx->frames[1].avf->pts);
+        alpha = av_clip(alpha, 0, ALPHA_MAX);
+    } else {
+        av_log(ctx, AV_LOG_DEBUG, "duplicate input PTS detected\n");
+        alpha = 0;
+    }
     if (alpha == 0 || alpha == ALPHA_MAX) {
         av_frame_copy(avf_out, alpha ? mi_ctx->frames[2].avf : mi_ctx->frames[1].avf);
         return;
-- 
2.43.0

