[FFmpeg-devel] [PATCH 1/2] avformat: Add recursion limit

* [FFmpeg-devel] [PATCH 1/2] avformat: Add recursion limit
@ 2025-07-07 10:31 Michael Niedermayer
  2025-07-07 10:31 ` [FFmpeg-devel] [PATCH 2/2] avformat/concatdec: Check recursion depth Michael Niedermayer
  0 siblings, 1 reply; 6+ messages in thread
From: Michael Niedermayer @ 2025-07-07 10:31 UTC (permalink / raw)
  To: FFmpeg development discussions and patches; +Cc: Yuhao Jiang

This is a generic recursion limit that is not specific to a demuxer
it does change public API which makes this unsuitable for backporting

Fixes: self_ref.ffconcat

Reported-by: Yuhao Jiang <danisjiang@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/avformat.c      | 5 +++++
 libavformat/avformat.h      | 9 +++++++++
 libavformat/options_table.h | 1 +
 3 files changed, 15 insertions(+)

diff --git a/libavformat/avformat.c b/libavformat/avformat.c
index 18ca4643eec..dca46395ac7 100644
--- a/libavformat/avformat.c
+++ b/libavformat/avformat.c
@@ -844,6 +844,11 @@ int ff_copy_whiteblacklists(AVFormatContext *dst, const AVFormatContext *src)
             *(char **)((char*)dst + offsets[i]) = dst_str;
         }
     }
+    if (src->recursion_limit <= 0) {
+        av_log(dst, AV_LOG_ERROR, "Too deep recursion\n");
+        return AVERROR(ELOOP);
+    }
+    dst->recursion_limit = src->recursion_limit - 1;
     return 0;
 }
 
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index b6c63e22376..ef1cf5d5a76 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1884,6 +1884,15 @@ typedef struct AVFormatContext {
      * @see skip_estimate_duration_from_pts
      */
     int64_t duration_probesize;
+
+    /**
+     * Depth recursion limit,
+     *
+     * The maximum recursion depth that a Demuxer can open a Demuxer within itself.
+     *
+     * - demuxing: Set by user
+     */
+    int recursion_limit;
 } AVFormatContext;
 
 /**
diff --git a/libavformat/options_table.h b/libavformat/options_table.h
index e2e690fd2ae..8275570dae6 100644
--- a/libavformat/options_table.h
+++ b/libavformat/options_table.h
@@ -106,6 +106,7 @@ static const AVOption avformat_options[] = {
 {"skip_estimate_duration_from_pts", "skip duration calculation in estimate_timings_from_pts", OFFSET(skip_estimate_duration_from_pts), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, D},
 {"max_probe_packets", "Maximum number of packets to probe a codec", OFFSET(max_probe_packets), AV_OPT_TYPE_INT, { .i64 = 2500 }, 0, INT_MAX, D },
 {"duration_probesize", "Maximum number of bytes to probe the durations of the streams in estimate_timings_from_pts", OFFSET(duration_probesize), AV_OPT_TYPE_INT64, {.i64 = 0 }, 0, INT64_MAX, D},
+{"recursion_limit", "Maximum number of times a demuxer can recursively be opened", OFFSET(recursion_limit), AV_OPT_TYPE_INT, {.i64 = 10 }, 0, INT64_MAX, D},
 {NULL},
 };
 
-- 
2.49.0

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