[FFmpeg-devel] [PATCH 3/3] Revert "avcodec/h264_mp4toannexb_bsf: fix missing PS before IDR frames"

[Michael Niedermayer <michael@niedermayer.cc>]

This reverts commit d3aa0cd16f5e952bc346b7c74b4dcba95151a63a.

Fixes: out of array write
Fixes: 64407/clusterfuzz-testcase-minimized-ffmpeg_BSF_H264_MP4TOANNEXB_fuzzer-4966763443650560

The bsf code performs 2 iterations, the first counts how much space is needed
than allocates
and the 2nd pass copies into teh allocated space

The reverted code reallocates sps/pps in the first pass in a data dependant way that leaves
the 2nd pass in a different state then the first

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/bsf/h264_mp4toannexb.c | 83 +++----------------------------
 tests/fate/h264.mak               |  5 --
 2 files changed, 6 insertions(+), 82 deletions(-)

diff --git a/libavcodec/bsf/h264_mp4toannexb.c b/libavcodec/bsf/h264_mp4toannexb.c
index 120241c892..b99de39ce9 100644
--- a/libavcodec/bsf/h264_mp4toannexb.c
+++ b/libavcodec/bsf/h264_mp4toannexb.c
@@ -36,8 +36,6 @@ typedef struct H264BSFContext {
     uint8_t *pps;
     int      sps_size;
     int      pps_size;
-    unsigned sps_buf_size;
-    unsigned pps_buf_size;
     uint8_t  length_size;
     uint8_t  new_idr;
     uint8_t  idr_sps_seen;
@@ -133,33 +131,16 @@ pps:
         memset(out + total_size, 0, padding);
 
     if (pps_offset) {
-        uint8_t *sps;
-
+        s->sps      = out;
         s->sps_size = pps_offset;
-        sps = av_fast_realloc(s->sps, &s->sps_buf_size, s->sps_size);
-        if (!sps) {
-            av_free(out);
-            return AVERROR(ENOMEM);
-        }
-        s->sps = sps;
-        memcpy(s->sps, out, s->sps_size);
     } else {
         av_log(ctx, AV_LOG_WARNING,
                "Warning: SPS NALU missing or invalid. "
                "The resulting stream may not play.\n");
     }
     if (pps_offset < total_size) {
-        uint8_t *pps;
-
+        s->pps      = out + pps_offset;
         s->pps_size = total_size - pps_offset;
-        pps = av_fast_realloc(s->pps, &s->pps_buf_size, s->pps_size);
-        if (!pps) {
-            av_freep(&s->sps);
-            av_free(out);
-            return AVERROR(ENOMEM);
-        }
-        s->pps = pps;
-        memcpy(s->pps, out + pps_offset, s->pps_size);
     } else {
         av_log(ctx, AV_LOG_WARNING,
                "Warning: PPS NALU missing or invalid. "
@@ -179,35 +160,6 @@ pps:
     return 0;
 }
 
-static int h264_mp4toannexb_save_ps(uint8_t **dst, int *dst_size,
-                                    unsigned *dst_buf_size,
-                                    const uint8_t *nal, uint32_t nal_size,
-                                    int first)
-{
-    static const uint8_t nalu_header[4] = { 0, 0, 0, 1 };
-    const int start_code_size = sizeof(nalu_header);
-    uint8_t *ptr;
-    uint32_t size;
-
-    if (first)
-        size = 0;
-    else
-        size = *dst_size;
-
-    ptr = av_fast_realloc(*dst, dst_buf_size, size + nal_size + start_code_size);
-    if (!ptr)
-        return AVERROR(ENOMEM);
-
-    memcpy(ptr + size, nalu_header, start_code_size);
-    size += start_code_size;
-    memcpy(ptr + size, nal, nal_size);
-    size += nal_size;
-
-    *dst = ptr;
-    *dst_size = size;
-    return 0;
-}
-
 static int h264_mp4toannexb_init(AVBSFContext *ctx)
 {
     int extra_size = ctx->par_in->extradata_size;
@@ -268,9 +220,6 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *opkt)
     if (j) \
         av_log(__VA_ARGS__)
     for (int j = 0; j < 2; j++) {
-        int sps_count = 0;
-        int pps_count = 0;
-
         buf      = in->data;
         new_idr  = s->new_idr;
         sps_seen = s->idr_sps_seen;
@@ -301,18 +250,8 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *opkt)
 
             if (unit_type == H264_NAL_SPS) {
                 sps_seen = new_idr = 1;
-                if (!j) {
-                    h264_mp4toannexb_save_ps(&s->sps, &s->sps_size, &s->sps_buf_size,
-                                             buf, nal_size, !sps_count);
-                    sps_count++;
-                }
             } else if (unit_type == H264_NAL_PPS) {
                 pps_seen = new_idr = 1;
-                if (!j) {
-                    h264_mp4toannexb_save_ps(&s->pps, &s->pps_size, &s->pps_buf_size,
-                                             buf, nal_size, !pps_count);
-                    pps_count++;
-                }
                 /* if SPS has not been seen yet, prepend the AVCC one to PPS */
                 if (!sps_seen) {
                     if (!s->sps_size) {
@@ -332,10 +271,9 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *opkt)
 
             /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */
             if (new_idr && unit_type == H264_NAL_IDR_SLICE && !sps_seen && !pps_seen) {
-                if (s->sps_size)
-                    count_or_copy(&out, &out_size, s->sps, s->sps_size, PS_OUT_OF_BAND, j);
-                if (s->pps_size)
-                    count_or_copy(&out, &out_size, s->pps, s->pps_size, PS_OUT_OF_BAND, j);
+                if (ctx->par_out->extradata)
+                    count_or_copy(&out, &out_size, ctx->par_out->extradata,
+                                  ctx->par_out->extradata_size, PS_OUT_OF_BAND, j);
                 new_idr = 0;
             /* if only SPS has been seen, also insert PPS */
             } else if (new_idr && unit_type == H264_NAL_IDR_SLICE && sps_seen && !pps_seen) {
@@ -351,7 +289,7 @@ static int h264_mp4toannexb_filter(AVBSFContext *ctx, AVPacket *opkt)
             else
                 ps = PS_NONE;
             count_or_copy(&out, &out_size, buf, nal_size, ps, j);
-            if (unit_type == H264_NAL_SLICE) {
+            if (!new_idr && unit_type == H264_NAL_SLICE) {
                 new_idr  = 1;
                 sps_seen = 0;
                 pps_seen = 0;
@@ -391,14 +329,6 @@ fail:
     return ret;
 }
 
-static void h264_mp4toannexb_close(AVBSFContext *ctx)
-{
-    H264BSFContext *s = ctx->priv_data;
-
-    av_freep(&s->sps);
-    av_freep(&s->pps);
-}
-
 static void h264_mp4toannexb_flush(AVBSFContext *ctx)
 {
     H264BSFContext *s = ctx->priv_data;
@@ -418,6 +348,5 @@ const FFBitStreamFilter ff_h264_mp4toannexb_bsf = {
     .priv_data_size = sizeof(H264BSFContext),
     .init           = h264_mp4toannexb_init,
     .filter         = h264_mp4toannexb_filter,
-    .close          = h264_mp4toannexb_close,
     .flush          = h264_mp4toannexb_flush,
 };
diff --git a/tests/fate/h264.mak b/tests/fate/h264.mak
index 674054560b..d0c57eabe9 100644
--- a/tests/fate/h264.mak
+++ b/tests/fate/h264.mak
@@ -227,7 +227,6 @@ FATE_H264-$(call FRAMECRC, MOV, H264) += fate-h264-twofields-packet
 FATE_H264-$(call DEMMUX, MOV, H264, H264_MP4TOANNEXB_BSF SCALE_FILTER) += fate-h264-bsf-mp4toannexb-new-extradata
 
 FATE_H264-$(call DEMMUX, MOV, H264, H264_MP4TOANNEXB_BSF) += fate-h264-bsf-mp4toannexb \
-                                                             fate-h264-bsf-mp4toannexb-2 \
                                                              fate-h264_mp4toannexb_ticket5927 \
                                                              fate-h264_mp4toannexb_ticket5927_2 \
 
@@ -432,10 +431,6 @@ fate-h264-conformance-sva_nl1_b:                  CMD = framecrc -i $(TARGET_SAM
 fate-h264-conformance-sva_nl2_e:                  CMD = framecrc -i $(TARGET_SAMPLES)/h264-conformance/SVA_NL2_E.264
 
 fate-h264-bsf-mp4toannexb:                        CMD = md5 -i $(TARGET_SAMPLES)/h264/interlaced_crop.mp4 -c:v copy -f h264
-# First IDR is prefixed by SPS/PPS
-fate-h264-bsf-mp4toannexb-2:                      CMD = md5 -i $(TARGET_SAMPLES)/h264/ps_prefix_first_idr.mp4 -c:v copy -f h264
-fate-h264-bsf-mp4toannexb-2:                      CMP = oneline
-fate-h264-bsf-mp4toannexb-2:                      REF = cffcfa6a2d0b58c9de1f5785f099f41d
 fate-h264-bsf-mp4toannexb-new-extradata:          CMD = stream_remux mov $(TARGET_SAMPLES)/h264/extradata-reload-multi-stsd.mov "" h264 "-map 0:v"
 fate-h264_mp4toannexb_ticket5927:                 CMD = transcode "mp4" $(TARGET_SAMPLES)/h264/thezerotheorem-cut.mp4 \
                                                         h264 "-c:v copy -bsf:v h264_mp4toannexb -an" "-c:v copy"
-- 
2.17.1

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