Backport of upstream commit b1942734c7cbcdc9034034373abcc9ecb9644c47 for 
CVE-2023-50007 to release/5.0.

The release/5.0 branch is still affected by CVE-2023-50007.
The upstream patch does not apply cleanly due to code differences,
so this patch manually adapts the fix while preserving the original logic.

A crafted input can trigger a negative-size-param bug in 
av_samples_set_silence()
in libavutil/samplefmt.c. The issue is caused by improper handling of the size 
parameter
in the av_samples_set_silence function, which can lead to undefined behavior or 
crashes.

This patch fixes the issue by ensuring that the size parameter is non-negative 
before
being used in the function, preventing invalid memory operations. Fix #22775.

Reproducer triggers a crash before the patch is applied, and works
as expected after applying the patch.

Associated issue: https://code.ffmpeg.org/FFmpeg/FFmpeg/issues/22775
Fix #22775

CVE: CVE-2023-50007
Found-by: Zeng Yunxiang

Signed-off-by: lizhixuan.HUST <[email protected]>
---
 libavfilter/af_afwtdn.c | 34 +++++++++++++++++++---------------
 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/libavfilter/af_afwtdn.c b/libavfilter/af_afwtdn.c
index 09b504d634..1839190736 100644
--- a/libavfilter/af_afwtdn.c
+++ b/libavfilter/af_afwtdn.c
@@ -410,6 +410,7 @@ typedef struct AudioFWTDNContext {
 
     uint64_t sn;
     int64_t eof_pts;
+    int eof;
 
     int wavelet_type;
     int channels;
@@ -1071,7 +1072,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
         s->drop_samples = 0;
     } else {
         if (s->padd_samples < 0 && eof) {
-            out->nb_samples += s->padd_samples;
+            out->nb_samples = FFMAX(0, out->nb_samples + s->padd_samples);
             s->padd_samples = 0;
         }
         if (!eof)
@@ -1210,23 +1211,26 @@ static int activate(AVFilterContext *ctx)
 
     FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
 
-    ret = ff_inlink_consume_samples(inlink, s->nb_samples, s->nb_samples, &in);
-    if (ret < 0)
-        return ret;
-    if (ret > 0)
-        return filter_frame(inlink, in);
+    if (!s->eof) {
+        ret = ff_inlink_consume_samples(inlink, s->nb_samples, s->nb_samples, 
&in);
+        if (ret < 0)
+            return ret;
+        if (ret > 0)
+            return filter_frame(inlink, in);
+    }
 
     if (ff_inlink_acknowledge_status(inlink, &status, &pts)) {
-        if (status == AVERROR_EOF) {
-            while (s->padd_samples != 0) {
-                ret = filter_frame(inlink, NULL);
-                if (ret < 0)
-                    return ret;
-            }
-            ff_outlink_set_status(outlink, status, pts);
-            return ret;
-        }
+        if (status == AVERROR_EOF)
+            s->eof = 1;
     }
+
+    if (s->eof && s->padd_samples != 0) {
+        return filter_frame(inlink, NULL);
+    } else if (s->eof) {
+        ff_outlink_set_status(outlink, AVERROR_EOF, s->eof_pts);
+        return 0;
+    }
+
     FF_FILTER_FORWARD_WANTED(outlink, inlink);
 
     return FFERROR_NOT_READY;
-- 
2.34.1

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