ff_id3v2_read: add option to limit ID3 magic number search

Several chunked formats (AIFF, IFF,DSF) store ID3 metadata within an 'ID3 '
chunk tag. If such chunks are stored sequentially, it is possible for the
ID3v2 parser to confuse the chunk tag for the ID3 magic number. e.g.

[1st chunk tag ('ID3 ') | chunk size] [ID3 magic number | metadata ...]
[2nd chunk tag ('ID3 ') | chunk size] [ID3 magic number | metadata ...]

Fixes ticket #3530.

Signed-off-by: Peter Ross <pross@xvid.org>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 5331773cc33ba26b9e26ace643d926219e46a17b)

Conflicts:
	libavformat/dsfdec.c
	libavformat/id3v2.c

6 files changed, 20 insertions, 7 deletions

diff --git a/libavformat/aiffdec.c b/libavformat/aiffdec.c
index 4a2629888b..396abb162d 100644
--- a/libavformat/aiffdec.c
+++ b/libavformat/aiffdec.c
@@ -237,7 +237,7 @@ static int aiff_read_header(AVFormatContext *s)
             break;
         case MKTAG('I', 'D', '3', ' '):
             position = avio_tell(pb);
-            ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
+            ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta, size);
             if (id3v2_extra_meta)
                 if ((ret = ff_id3v2_parse_apic(s, &id3v2_extra_meta)) < 0) {
                     ff_id3v2_free_extra_meta(&id3v2_extra_meta);
diff --git a/libavformat/asfdec.c b/libavformat/asfdec.c
index de42b45a8e..74201cff1a 100644
--- a/libavformat/asfdec.c
+++ b/libavformat/asfdec.c
@@ -268,7 +268,7 @@ static void get_id3_tag(AVFormatContext *s, int len)
 {
     ID3v2ExtraMeta *id3v2_extra_meta = NULL;
 
-    ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
+    ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta, len);
     if (id3v2_extra_meta)
         ff_id3v2_parse_apic(s, &id3v2_extra_meta);
     ff_id3v2_free_extra_meta(&id3v2_extra_meta);
diff --git a/libavformat/id3v2.c b/libavformat/id3v2.c
index 2e8d06d6b0..8fdcc8a032 100644
--- a/libavformat/id3v2.c
+++ b/libavformat/id3v2.c
@@ -777,17 +777,28 @@ seek:
     return;
 }
 
-void ff_id3v2_read(AVFormatContext *s, const char *magic, ID3v2ExtraMeta **extra_meta)
+void ff_id3v2_read(AVFormatContext *s, const char *magic, ID3v2ExtraMeta **extra_meta,
+                   unsigned int max_search_size)
 {
     int len, ret;
     uint8_t buf[ID3v2_HEADER_SIZE];
     int     found_header;
-    int64_t off;
+    int64_t start, off;
 
+    if (max_search_size && max_search_size < ID3v2_HEADER_SIZE)
+        return;
+
+    start = avio_tell(s->pb);
     do {
         /* save the current offset in case there's nothing to read/skip */
         off = avio_tell(s->pb);
         ret = avio_read(s->pb, buf, ID3v2_HEADER_SIZE);
+        if (max_search_size && off - start >= max_search_size - ID3v2_HEADER_SIZE) {
+            avio_seek(s->pb, off, SEEK_SET);
+            break;
+        }
+
+        ret = avio_read(s->pb, buf, ID3v2_HEADER_SIZE);
         if (ret != ID3v2_HEADER_SIZE) {
             avio_seek(s->pb, off, SEEK_SET);
             break;
diff --git a/libavformat/id3v2.h b/libavformat/id3v2.h
index f7270106a1..4fe59a5477 100644
--- a/libavformat/id3v2.h
+++ b/libavformat/id3v2.h
@@ -93,8 +93,10 @@ int ff_id3v2_tag_len(const uint8_t *buf);
  * Read an ID3v2 tag, including supported extra metadata
  * @param extra_meta If not NULL, extra metadata is parsed into a list of
  * ID3v2ExtraMeta structs and *extra_meta points to the head of the list
+ * @param[opt] max_search_search restrict ID3 magic number search (bytes from start)
  */
-void ff_id3v2_read(AVFormatContext *s, const char *magic, ID3v2ExtraMeta **extra_meta);
+void ff_id3v2_read(AVFormatContext *s, const char *magic, ID3v2ExtraMeta **extra_meta,
+                   unsigned int max_search_size);
 
 /**
  * Initialize an ID3v2 tag.
diff --git a/libavformat/omadec.c b/libavformat/omadec.c
index 8d29675c1c..34d63a377c 100644
--- a/libavformat/omadec.c
+++ b/libavformat/omadec.c
@@ -275,7 +275,7 @@ static int oma_read_header(AVFormatContext *s)
     ID3v2ExtraMeta *extra_meta = NULL;
     OMAContext *oc = s->priv_data;
 
-    ff_id3v2_read(s, ID3v2_EA3_MAGIC, &extra_meta);
+    ff_id3v2_read(s, ID3v2_EA3_MAGIC, &extra_meta, 0);
     ret = avio_read(s->pb, buf, EA3_HEADER_SIZE);
     if (ret < EA3_HEADER_SIZE)
         return -1;
diff --git a/libavformat/utils.c b/libavformat/utils.c
index d32f584197..821b23d642 100644
--- a/libavformat/utils.c
+++ b/libavformat/utils.c
@@ -620,7 +620,7 @@ int avformat_open_input(AVFormatContext **ps, const char *filename, AVInputForma
 
     /* e.g. AVFMT_NOFILE formats will not have a AVIOContext */
     if (s->pb)
-        ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta);
+        ff_id3v2_read(s, ID3v2_DEFAULT_MAGIC, &id3v2_extra_meta, 0);
 
     if (!(s->flags&AVFMT_FLAG_PRIV_OPT) && s->iformat->read_header)
         if ((ret = s->iformat->read_header(s)) < 0)