[FFmpeg-devel] [PATCH v6] Fix integer parameters size check in SDP fmtp line
Olivier Maignial
olivier.maignial at smile.fr
Fri Jul 12 09:40:40 EEST 2019
=== PROBLEM ===
I was trying to record h264 + aac streams from an RTSP server to mp4 file. using this command line:
ffmpeg -v verbose -y -i "rtsp://<ip>/my_resources" -codec copy -bsf:a aac_adtstoasc test.mp4
FFmpeg then fail to record audio and output this logs:
[rtsp @ 0xcda1f0] The profile-level-id field size is invalid (40)
[rtsp @ 0xcda1f0] Error parsing AU headers
...
[rtsp @ 0xcda1f0] Could not find codec parameters for stream 1 (Audio: aac, 48000 Hz, 1 channels): unspecified sample format
In SDP provided by my RTSP server I had this fmtp line:
a=fmtp:98 streamType=5; profile-level-id=40; mode=AAC-hbr; config=1188; sizeLength=13; indexLength=3; indexDeltaLength=3;
In FFmpeg code, I found a check introduced by commit 24130234cd9dd733116d17b724ea4c8e12ce097a. It disallows values greater than 32 for fmtp line parameters.
However, In RFC-6416 (RTP Payload Format for MPEG-4 Audio/Visual Streams) give examples of "profile-level-id" values for AAC, up to 55.
Furthermore, RFC-4566 (SDP: Session Description Protocol) do not give any limit of size on interger parameters given in fmtp line.
=== FIX ===
Instead of prohibit values over 32, I propose to check the possible integer overflow.
The use of strtoll allow to check the string validity and the possible overflow.
Value is then checked against INT32_MIN and INT32_MAX. Using INT32_MIN/MAX ensure to have the same behavior on 32 or 64 bits platforms.
This patch fix my problem and I now can record my RTSP AAC stream to mp4.
It has passed the full fate tests suite sucessfully.
Signed-off-by: Olivier Maignial <olivier.maignial at smile.fr>
---
Changes V6 --> V7:
- Use long long int and strtoll. LLONG_MAX is always greather than INT32_MIN while LONG_MAX can be equal to INT32_MAX. It allows to accept full INT32 range.
- Avoid to use errno
libavformat/rtpdec_mpeg4.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/libavformat/rtpdec_mpeg4.c b/libavformat/rtpdec_mpeg4.c
index 4f70599..f1cbedf 100644
--- a/libavformat/rtpdec_mpeg4.c
+++ b/libavformat/rtpdec_mpeg4.c
@@ -289,15 +289,18 @@ static int parse_fmtp(AVFormatContext *s,
for (i = 0; attr_names[i].str; ++i) {
if (!av_strcasecmp(attr, attr_names[i].str)) {
if (attr_names[i].type == ATTR_NAME_TYPE_INT) {
- int val = atoi(value);
- if (val > 32) {
+ char *end_ptr = NULL;
+ long long int val = strtoll(value, &end_ptr, 10);
+ if (end_ptr == value || end_ptr[0] != '\0' ||
+ val < INT32_MIN || val > INT32_MAX) {
av_log(s, AV_LOG_ERROR,
- "The %s field size is invalid (%d)\n",
- attr, val);
+ "The %s field value is not a valid number, or overflows int32: %s\n",
+ attr, value);
return AVERROR_INVALIDDATA;
}
+
*(int *)((char *)data+
- attr_names[i].offset) = val;
+ attr_names[i].offset) = (int) val;
} else if (attr_names[i].type == ATTR_NAME_TYPE_STR) {
char *val = av_strdup(value);
if (!val)
--
2.7.4
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