[FFmpeg-devel] [PATCH 1/3] avcodec/mjpegbdec: Set buf_size

[FFmpeg-devel] [PATCH 1/3] avcodec/mjpegbdec: Set buf_size

[Michael Niedermayer]

Fixes: Timeout
Fixes: 45170/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MJPEGB_fuzzer-5874820431085568

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

diff --git a/libavcodec/mjpegbdec.c b/libavcodec/mjpegbdec.c
index 218be41192..c3d3125142 100644
--- a/libavcodec/mjpegbdec.c
+++ b/libavcodec/mjpegbdec.c
@@ -57,6 +57,7 @@ static int mjpegb_decode_frame(AVCodecContext *avctx,
     buf_end = buf + buf_size;
     s->got_picture = 0;
     s->adobe_transform = -1;
+    s->buf_size = buf_size;
 
 read_header:
     /* reset on every SOI */
-- 
2.17.1

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[FFmpeg-devel] [PATCH 2/3] tools/target_dec_fuzzer: Adjust threshold for DFA

[Michael Niedermayer]

Fixes: Timeout
Fixes: 45351/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DFA_fuzzer-5768895011618816

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

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index cef71e1e0a..23b0184059 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -157,6 +157,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_BINKVIDEO:   maxpixels  /= 32;    break;
     case AV_CODEC_ID_CFHD:        maxpixels  /= 128;   break;
     case AV_CODEC_ID_COOK:        maxsamples /= 1<<20; break;
+    case AV_CODEC_ID_DFA:         maxpixels  /= 1024;  break;
     case AV_CODEC_ID_DIRAC:       maxpixels  /= 8192;  break;
     case AV_CODEC_ID_DST:         maxsamples /= 1<<20; break;
     case AV_CODEC_ID_DVB_SUBTITLE: av_dict_set_int(&opts, "compute_clut", -2, 0); break;
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 2/3] tools/target_dec_fuzzer: Adjust threshold for DFA

[Michael Niedermayer]

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On Fri, Mar 11, 2022 at 09:20:24PM +0100, Michael Niedermayer wrote:
> Fixes: Timeout
> Fixes: 45351/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DFA_fuzzer-5768895011618816
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  tools/target_dec_fuzzer.c | 1 +
>  1 file changed, 1 insertion(+)

will apply

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

The worst form of inequality is to try to make unequal things equal.
-- Aristotle

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[FFmpeg-devel] [PATCH 3/3] avcodec/dfa: Optimize output reshuffle loop

[Michael Niedermayer]

18035 -> 4018 dezicycles (Tested with LOGOS.DFA, gcc 7, 3950X)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/dfa.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/libavcodec/dfa.c b/libavcodec/dfa.c
index 0cf3641a38..ab78d66763 100644
--- a/libavcodec/dfa.c
+++ b/libavcodec/dfa.c
@@ -388,9 +388,17 @@ static int dfa_decode_frame(AVCodecContext *avctx,
     for (i = 0; i < avctx->height; i++) {
         if(version == 0x100) {
             int j;
-            for(j = 0; j < avctx->width; j++) {
-                dst[j] = buf[ (i&3)*(avctx->width /4) + (j/4) +
-                             ((j&3)*(avctx->height/4) + (i/4))*avctx->width];
+            const uint8_t *buf1 = buf + (i&3)*(avctx->width/4) + (i/4)*avctx->width;
+            int stride = (avctx->height/4)*avctx->width;
+            for(j = 0; j < avctx->width/4; j++) {
+                dst[4*j+0] = buf1[j + 0*stride];
+                dst[4*j+1] = buf1[j + 1*stride];
+                dst[4*j+2] = buf1[j + 2*stride];
+                dst[4*j+3] = buf1[j + 3*stride];
+            }
+            j *= 4;
+            for(; j < avctx->width; j++) {
+                dst[j] = buf1[(j/4) + (j&3)*stride];
             }
         } else {
             memcpy(dst, buf, avctx->width);
-- 
2.17.1

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Re: [FFmpeg-devel] [PATCH 3/3] avcodec/dfa: Optimize output reshuffle loop

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 609 bytes --]

On Fri, Mar 11, 2022 at 09:20:25PM +0100, Michael Niedermayer wrote:
> 18035 -> 4018 dezicycles (Tested with LOGOS.DFA, gcc 7, 3950X)
> 
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/dfa.c | 14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)

will apply

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

Many that live deserve death. And some that die deserve life. Can you give
it to them? Then do not be too eager to deal out death in judgement. For
even the very wise cannot see all ends. -- Gandalf

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Re: [FFmpeg-devel] [PATCH 1/3] avcodec/mjpegbdec: Set buf_size

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 809 bytes --]

On Fri, Mar 11, 2022 at 09:20:23PM +0100, Michael Niedermayer wrote:
> Fixes: Timeout
> Fixes: 45170/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MJPEGB_fuzzer-5874820431085568
> 
> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
> ---
>  libavcodec/mjpegbdec.c | 1 +
>  1 file changed, 1 insertion(+)

will apply

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

Awnsering whenever a program halts or runs forever is
On a turing machine, in general impossible (turings halting problem).
On any real computer, always possible as a real computer has a finite number
of states N, and will either halt in less than N cycles or never halt.

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