[FFmpeg-devel] [PR] avformat: Add ff_format_check_set_url() and use in rtsp (PR #22292)

[michaelni via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>]

PR #22292 opened by michaelni
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/22292
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/22292.patch

avformat/rtsp: Use ff_format_check_set_url() ...
Fixes: redirect to blacklisted protocol
Fixes: YWH-PGM40646-41

Found-by: BapToutatis
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>


From fc083ce5e2edcb5cbf6d6bdae8456020dc6403dc Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Thu, 26 Feb 2026 03:05:36 +0100
Subject: [PATCH 1/2] avformat: Add ff_format_check_set_url()

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/avformat.c | 31 +++++++++++++++++++++++++++++++
 libavformat/internal.h | 10 ++++++++++
 2 files changed, 41 insertions(+)

diff --git a/libavformat/avformat.c b/libavformat/avformat.c
index 806f8dcab2..3b78da6078 100644
--- a/libavformat/avformat.c
+++ b/libavformat/avformat.c
@@ -868,6 +868,37 @@ void ff_format_set_url(AVFormatContext *s, char *url)
     s->url = url;
 }
 
+int ff_format_check_set_url(AVFormatContext *s, char *url)
+{
+    av_assert0(url);
+    char proto[64];
+    char auth[256];
+    char host[256];
+    char path[256];
+    int port=-1;
+
+    av_url_split(proto, sizeof(proto), auth, sizeof(auth), host, sizeof(host), &port, path, sizeof(path), url);
+
+    if (s->protocol_whitelist && av_match_list(proto, s->protocol_whitelist, ',') <= 0) {
+        av_log(s, AV_LOG_ERROR, "Protocol '%s' not on whitelist '%s'!\n", proto, s->protocol_whitelist);
+        return AVERROR(EINVAL);
+    }
+
+    if (s->protocol_blacklist && av_match_list(proto, s->protocol_blacklist, ',') > 0) {
+        av_log(s, AV_LOG_ERROR, "Protocol '%s' on blacklist '%s'!\n", proto, s->protocol_blacklist);
+        return AVERROR(EINVAL);
+    }
+
+    url = av_strdup(url);
+    if (!url)
+        return AVERROR(ENOMEM);
+
+    av_freep(&s->url);
+    s->url = url;
+    return 0;
+}
+
+
 int ff_format_io_close(AVFormatContext *s, AVIOContext **pb)
 {
     int ret = 0;
diff --git a/libavformat/internal.h b/libavformat/internal.h
index 64452cce6e..06ddb569de 100644
--- a/libavformat/internal.h
+++ b/libavformat/internal.h
@@ -630,6 +630,16 @@ int ff_bprint_to_codecpar_extradata(AVCodecParameters *par, struct AVBPrint *buf
  */
 void ff_format_set_url(AVFormatContext *s, char *url);
 
+/**
+ * Set AVFormatContext url field to a av_strdup of the provided pointer. The pointer must
+ * point to a valid string. The existing url field is freed if necessary.
+ *
+ * Checks protocol_whitelist/blacklist
+ *
+ * @returns a AVERROR code or non negative on success
+ */
+int ff_format_check_set_url(AVFormatContext *s, char *url);
+
 /**
  * Return a positive value if the given url has one of the given
  * extensions, negative AVERROR on error, 0 otherwise.
-- 
2.52.0


From f62a4939418537ee92f0aa2b472a4666a5f379f2 Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michael@niedermayer.cc>
Date: Thu, 26 Feb 2026 03:08:36 +0100
Subject: [PATCH 2/2] avformat/rtsp: Use ff_format_check_set_url()

Fixes: redirect to blacklisted protocol
Fixes: YWH-PGM40646-41

Found-by: BapToutatis
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavformat/rtsp.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
index 822780087d..aaad565c2b 100644
--- a/libavformat/rtsp.c
+++ b/libavformat/rtsp.c
@@ -2170,12 +2170,11 @@ redirect:
     ff_rtsp_close_streams(s);
     ff_rtsp_close_connections(s);
     if (reply->status_code >=300 && reply->status_code < 400 && s->iformat) {
-        char *new_url = av_strdup(reply->location);
-        if (!new_url) {
-            err = AVERROR(ENOMEM);
+        int ret = ff_format_check_set_url(s, reply->location);
+        if (ret < 0) {
+            err = ret;
             goto fail2;
         }
-        ff_format_set_url(s, new_url);
         rt->session_id[0] = '\0';
         av_log(s, AV_LOG_INFO, "Status %d: Redirecting to %s\n",
                reply->status_code,
-- 
2.52.0

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