Project: gpac (gpac/gpac), language: c++
Vulnerability instance: gpac.cve-2020-6631
Sanitizer: address

================= Bug Report (1/1) ==================
## Source: GitHub Issue
## URL: https://github.com/gpac/gpac/issues/1378
## Description:
Issue: gpac/gpac#1378
Title: null pointer reference in gf_m2ts_stream_process_pmt
State: closed
Created by: cuanduo
Created at: 2020-01-02 00:49:55+00:00

Issue Body:
Thanks for reporting your issue. Please make sure these boxes are checked before submitting your issue - thank you!

- [ yes] I looked for a similar issue and couldn't find any.
- [ yes] I tried with the latest version of GPAC. Installers available at http://gpac.io/downloads/gpac-nightly-builds/
- [ yes] I give enough information for contributors to reproduce my issue (meaningful title, github labels, platform and compiler, command-line ...). I can share files anonymously with this dropbox: https://www.mediafire.com/filedrop/filedrop_hosted.php?drop=eec9e058a9486fe4e99c33021481d9e1826ca9dbc242a6cfaab0fe95da5e5d95

Detailed guidelines: http://gpac.io/2013/07/16/how-to-file-a-bug-properly/

MP42TS -src $POC -dst-file /dev/null

[count_video1.zip](https://github.com/gpac/gpac/files/4014702/count_video1.zip)
asan output
```
root@ubuntu:/home/tim/gpac# ../gpac-asan/MP42TS -src crashes/count_video.mp4-signalb-0x198 -dst-file /dev/null
Setting up program ID 1 - send rates: PSI 200 ms PCR 100 ms - PCR offset 0
AddressSanitizer:DEADLYSIGNAL
=================================================================
==115151==ERROR: AddressSanitizer: SEGV on unknown address 0x000000000008 (pc 0x558236d3d311 bp 0x6080000008a0 sp 0x7ffd7d124a70 T0)
==115151==The signal is caused by a READ memory access.
==115151==Hint: address points to the zero page.
    #0 0x558236d3d310 in gf_m2ts_stream_process_pmt media_tools/m2ts_mux.c:718
    #1 0x558236d4dfd1 in gf_m2ts_mux_table_update_bitrate media_tools/m2ts_mux.c:256
    #2 0x558236d4dfd1 in gf_m2ts_mux_update_config media_tools/m2ts_mux.c:2543
    #3 0x558236bcfffd in main /home/tim/gpac-asan/applications/mp42ts/main.c:2684
    #4 0x7ff116424b6a in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x26b6a)
    #5 0x558236bd59c9 in _start (/home/tim/gpac-asan/MP42TS+0x1249c9)

AddressSanitizer can not provide additional info.
SUMMARY: AddressSanitizer: SEGV media_tools/m2ts_mux.c:718 in gf_m2ts_stream_process_pmt
==115151==ABORTING

```



Comments:
Comment by aureliendavid on 2020-01-08 15:42:11+00:00:
for this and #1377 my quick and dirty fix was to add a very ugly abort()

error handling is pretty terrible in mp42ts apart from a bunch of asserts (that are ignored when compiling in release mode), return values are rarely checked, etc. 

the abort should prevent afl/asan to detect it as a bug, and since it should only happen on very broken files it's not the end of the world, but it's still pretty ugly

if anyone has a better fix be my guest - in the meantime i'm closing the issue, reopen if needed

---

Comment by Beuc on 2020-01-17 15:09:51+00:00:
Hi,

I though I'd mention that abort() leads to mostly the same vulnerability (denial of service, in particular for a service that links to libgpac.so).
See for instance https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-9211

Attachments:
https://github.com/gpac/gpac/files/4014702/count_video1.zip

Commit References:
eec9e058a9486fe4e99c33021481d9e1826ca9db

Build script:
#!/bin/bash -eu
# Minimized build script with only core build commands
set -eu
./configure --static-build --extra-cflags="${CFLAGS}" --extra-ldflags="${CFLAGS}"
make -j$(nproc)

Dockerfile:
FROM hwiwonlee/secb.base:latest
RUN apt-get update && apt-get install -y build-essential pkg-config libz-dev
RUN git clone https://github.com/gpac/gpac gpac
RUN git -C gpac checkout 6b4ab401297be43b57f9eddd675971a8a5feab44
WORKDIR $SRC/gpac
COPY build.sh $SRC/

Additional files:
filename: fuzz_parse.c
content: /* Copyright 2021 Google LLC
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
      http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
#include <stdio.h>
#include <unistd.h>

#include <gpac/internal/isomedia_dev.h>
#include <gpac/constants.h>

int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
    char filename[256];
    sprintf(filename, "/tmp/libfuzzer.%d", getpid());

    FILE *fp = fopen(filename, "wb");
    if (!fp) {
        return 0;
    }
    fwrite(data, size, 1, fp);
    fclose(fp);

    GF_ISOFile *movie = NULL;
    movie = gf_isom_open_file(filename, GF_ISOM_OPEN_READ_DUMP, NULL);
    if (movie != NULL) {
        gf_isom_close(movie);
    }
    unlink(filename);
    return 0;
}