[FFmpeg-devel] [PATCH 1/3] avcodec/rka: use unsigned for buf0 additions

[FFmpeg-devel] [PATCH 1/3] avcodec/rka: use unsigned for buf0 additions

[Michael Niedermayer]

Fixes: signed integer overflow: -38912000 + -2109276160 cannot be represented in type 'int'
Fixes: 59670/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RKA_fuzzer-4987563245699072

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/rka.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/rka.c b/libavcodec/rka.c
index 76dca52602..d56f4faee4 100644
--- a/libavcodec/rka.c
+++ b/libavcodec/rka.c
@@ -735,10 +735,10 @@ static int decode_filter(RKAContext *s, ChContext *ctx, ACoder *ac, int off, uns
                     ctx->buf1[off] = (val + (sum >> bits)) * (1U << bits) +
                         (((1U << bits) - 1U) & ctx->buf1[off + -1]);
                 }
-                ctx->buf0[off] = ctx->buf1[off] + ctx->buf0[off + -1];
+                ctx->buf0[off] = ctx->buf1[off] + (unsigned)ctx->buf0[off + -1];
             } else {
                 val *= 1U << ctx->cmode;
-                sum += ctx->buf0[off + -1] + val;
+                sum += ctx->buf0[off + -1] + (unsigned)val;
                 switch (s->bps) {
                 case 16: sum = av_clip_int16(sum); break;
                 case  8: sum = av_clip_int8(sum);  break;
-- 
2.17.1

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[FFmpeg-devel] [PATCH 2/3] avcodec/mpegvideo_dec: consider interlaced lowres 4:2:0 chroma in edge emulation check better

[Michael Niedermayer]

Fixes: out of array read
Fixes: 59673/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG1VIDEO_fuzzer-5194311374077952

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/mpegvideo_dec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c
index 765ccd0ba4..c87ca77ae6 100644
--- a/libavcodec/mpegvideo_dec.c
+++ b/libavcodec/mpegvideo_dec.c
@@ -640,6 +640,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
     const int s_mask     = (2 << lowres) - 1;
     const int h_edge_pos = s->h_edge_pos >> lowres;
     const int v_edge_pos = s->v_edge_pos >> lowres;
+    int hc = s->chroma_y_shift ? (h+1-bottom_field)>>1 : h;
     linesize   = s->current_picture.f->linesize[0] << field_based;
     uvlinesize = s->current_picture.f->linesize[1] << field_based;
 
@@ -702,7 +703,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
     ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x;
 
     if ((unsigned) src_x > FFMAX( h_edge_pos - (!!sx) - 2 * block_s,       0) || uvsrc_y<0 ||
-        (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - h, 0)) {
+        (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - FFMAX(h, hc<<s->chroma_y_shift), 0)) {
         s->vdsp.emulated_edge_mc(s->sc.edge_emu_buffer, ptr_y,
                                  linesize >> field_based, linesize >> field_based,
                                  17, 17 + field_based,
@@ -747,7 +748,6 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s,
     pix_op[lowres - 1](dest_y, ptr_y, linesize, h, sx, sy);
 
     if (!CONFIG_GRAY || !(s->avctx->flags & AV_CODEC_FLAG_GRAY)) {
-        int hc = s->chroma_y_shift ? (h+1-bottom_field)>>1 : h;
         uvsx = (uvsx << 2) >> lowres;
         uvsy = (uvsy << 2) >> lowres;
         if (hc) {
-- 
2.17.1

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[FFmpeg-devel] [PATCH 3/3] avcodec/mpegvideo_dec: Add NULL pointer checks to MPV_motion_lowres()

[Michael Niedermayer]

This makes the null pointer checks match mpv_motion_internal()

Fixes: NULL pointer dereference
Fixes: 59671/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG1VIDEO_fuzzer-4993004566609920
Fixes: 59678/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEGVIDEO_fuzzer-4893168991338496

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/mpegvideo_dec.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c
index c87ca77ae6..fcca147cd6 100644
--- a/libavcodec/mpegvideo_dec.c
+++ b/libavcodec/mpegvideo_dec.c
@@ -885,10 +885,9 @@ static inline void MPV_motion_lowres(MpegEncContext *s,
                                s->mv[dir][1][0], s->mv[dir][1][1],
                                block_s, mb_y);
         } else {
-            if (s->picture_structure != s->field_select[dir][0] + 1 &&
-                s->pict_type != AV_PICTURE_TYPE_B && !s->first_field) {
+            if (   s->picture_structure != s->field_select[dir][0] + 1 && s->pict_type != AV_PICTURE_TYPE_B && !s->first_field
+                || !ref_picture[0]) {
                 ref_picture = s->current_picture_ptr->f->data;
-
             }
             mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
                                0, 0, s->field_select[dir][0],
@@ -901,8 +900,9 @@ static inline void MPV_motion_lowres(MpegEncContext *s,
         for (int i = 0; i < 2; i++) {
             uint8_t *const *ref2picture;
 
-            if (s->picture_structure == s->field_select[dir][i] + 1 ||
-                s->pict_type == AV_PICTURE_TYPE_B || s->first_field) {
+            if ((s->picture_structure == s->field_select[dir][i] + 1 ||
+                 s->pict_type == AV_PICTURE_TYPE_B || s->first_field) &&
+                ref_picture[0]) {
                 ref2picture = ref_picture;
             } else {
                 ref2picture = s->current_picture_ptr->f->data;
@@ -933,6 +933,9 @@ static inline void MPV_motion_lowres(MpegEncContext *s,
                 pix_op = s->h264chroma.avg_h264_chroma_pixels_tab;
             }
         } else {
+            if (!ref_picture[0]) {
+                ref_picture = s->current_picture_ptr->f->data;
+            }
             for (int i = 0; i < 2; i++) {
                 mpeg_motion_lowres(s, dest_y, dest_cb, dest_cr,
                                    0, 0, s->picture_structure != i + 1,
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 1/3] avcodec/rka: use unsigned for buf0 additions

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 710 bytes --]

On Thu, Jun 08, 2023 at 07:18:23PM +0200, Michael Niedermayer wrote:
> Fixes: signed integer overflow: -38912000 + -2109276160 cannot be represented in type 'int'
> Fixes: 59670/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_RKA_fuzzer-4987563245699072
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/rka.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)

will apply patchset

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have often repented speaking, but never of holding my tongue.
-- Xenocrates

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