[FFmpeg-devel] [PATCH v2 0/4] Minor fixes and for fuzzing targets

[FFmpeg-devel] [PATCH v2 0/4] Minor fixes and for fuzzing targets

[Kacper Michajłow]

Minor fixes and for fuzzing targets. Mostly motivated to reduce spam in
the build log. v2 only for rebase only.

Kacper Michajłow (4):
  tools/target_dec_fuzzer: move things to suppress
    Wdeclaration-after-statement
  tools/target_dec_fuzzer: suppress Wunused-function
  tools/target_dem_fuzzer: make fuzz data pointer constant
  tools/target_dem_fuzzer: remove unused fuzz_tag

 tools/target_dec_fuzzer.c | 34 +++++++++++++++++++++-------------
 tools/target_dem_fuzzer.c |  5 +----
 2 files changed, 22 insertions(+), 17 deletions(-)

-- 
2.49.0

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[FFmpeg-devel] [PATCH v2 1/4] tools/target_dec_fuzzer: move things to suppress Wdeclaration-after-statement

[Kacper Michajłow]

To avoid spam in log, each fuzzer is built separately so it's amplified
a lot.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 tools/target_dec_fuzzer.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index dfff167f78..7afb23619e 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -187,6 +187,13 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     uint64_t keyframes = 0;
     uint64_t flushpattern = -1;
     AVDictionary *opts = NULL;
+    AVCodecContext* ctx;
+    AVCodecContext* parser_avctx;
+    AVFrame *frame;
+    AVPacket *avpkt;
+    AVPacket *parsepkt;
+    int res;
+    int got_frame;
 
     if (!c) {
 #ifdef FFMPEG_DECODER
@@ -339,8 +346,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     maxsamples_per_frame = FFMIN(maxsamples_per_frame, maxsamples);
     maxpixels_per_frame  = FFMIN(maxpixels_per_frame , maxpixels);
 
-    AVCodecContext* ctx = avcodec_alloc_context3(&c->p);
-    AVCodecContext* parser_avctx = avcodec_alloc_context3(NULL);
+    ctx = avcodec_alloc_context3(&c->p);
+    parser_avctx = avcodec_alloc_context3(NULL);
     if (!ctx || !parser_avctx)
         error("Failed memory allocation");
 
@@ -470,7 +477,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
             ctx->width = ctx->height = 0;
     }
 
-    int res = avcodec_open2(ctx, &c->p, &opts);
+    res = avcodec_open2(ctx, &c->p, &opts);
     if (res < 0) {
         av_assert0(res != AVERROR_BUG);
         avcodec_free_context(&ctx);
@@ -483,11 +490,9 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     parser_avctx->extradata_size = ctx->extradata_size;
     parser_avctx->extradata      = ctx->extradata ? av_memdup(ctx->extradata, ctx->extradata_size + AV_INPUT_BUFFER_PADDING_SIZE) : NULL;
 
-
-    int got_frame;
-    AVFrame *frame = av_frame_alloc();
-    AVPacket *avpkt = av_packet_alloc();
-    AVPacket *parsepkt = av_packet_alloc();
+    frame = av_frame_alloc();
+    avpkt = av_packet_alloc();
+    parsepkt = av_packet_alloc();
     if (!frame || !avpkt || !parsepkt)
         error("Failed memory allocation");
 
@@ -563,7 +568,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
           // Iterate through all data
           while (decode_more && it++ < maxiteration) {
             av_frame_unref(frame);
-            int ret = decode_handler(ctx, frame, &got_frame, avpkt);
+            res = decode_handler(ctx, frame, &got_frame, avpkt);
 
             ec_pixels += (ctx->width + 32LL) * (ctx->height + 32LL);
             if (it > 20 || ec_pixels > 4 * ctx->max_pixels) {
@@ -582,15 +587,15 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
             if (nb_samples > maxsamples)
                 goto maximums_reached;
 
-            if (ret <= 0 || ret > avpkt->size)
+            if (res <= 0 || res > avpkt->size)
                break;
 
             if (ctx->codec_type == AVMEDIA_TYPE_SUBTITLE) {
-                avpkt->data += ret;
-                avpkt->size -= ret;
+                avpkt->data += res;
+                avpkt->size -= res;
                 decode_more = avpkt->size > 0;
             } else
-                decode_more = ret >= 0;
+                decode_more = res >= 0;
           }
           av_packet_unref(avpkt);
         }
-- 
2.49.0

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[FFmpeg-devel] [PATCH v2 2/4] tools/target_dec_fuzzer: suppress Wunused-function

[Kacper Michajłow]

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 tools/target_dec_fuzzer.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tools/target_dec_fuzzer.c b/tools/target_dec_fuzzer.c
index 7afb23619e..6950d134d9 100644
--- a/tools/target_dec_fuzzer.c
+++ b/tools/target_dec_fuzzer.c
@@ -72,6 +72,8 @@ static void error(const char *err)
 }
 
 static const FFCodec *c = NULL;
+
+#ifndef FFMPEG_DECODER
 static const FFCodec *AVCodecInitialize(enum AVCodecID codec_id)
 {
     const AVCodec *res;
@@ -81,6 +83,7 @@ static const FFCodec *AVCodecInitialize(enum AVCodecID codec_id)
         error("Failed to find decoder");
     return ffcodec(res);
 }
+#endif
 
 static int subtitle_handler(AVCodecContext *avctx, AVFrame *unused,
                             int *got_sub_ptr, const AVPacket *avpkt)
-- 
2.49.0

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[FFmpeg-devel] [PATCH v2 3/4] tools/target_dem_fuzzer: make fuzz data pointer constant

[Kacper Michajłow]

Mostly to avoid warnings.

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 tools/target_dem_fuzzer.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/target_dem_fuzzer.c b/tools/target_dem_fuzzer.c
index 8e96fad7f8..19bc1f09c1 100644
--- a/tools/target_dem_fuzzer.c
+++ b/tools/target_dem_fuzzer.c
@@ -29,7 +29,7 @@
 typedef struct IOContext {
     int64_t pos;
     int64_t filesize;
-    uint8_t *fuzz;
+    const uint8_t *fuzz;
     int fuzz_size;
 } IOContext;
 
-- 
2.49.0

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[FFmpeg-devel] [PATCH v2 4/4] tools/target_dem_fuzzer: remove unused fuzz_tag

[Kacper Michajłow]

Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
---
 tools/target_dem_fuzzer.c | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tools/target_dem_fuzzer.c b/tools/target_dem_fuzzer.c
index 19bc1f09c1..e169438ceb 100644
--- a/tools/target_dem_fuzzer.c
+++ b/tools/target_dem_fuzzer.c
@@ -98,10 +98,7 @@ static int64_t io_seek(void *opaque, int64_t offset, int whence)
 const uint32_t maxiteration = 8096;
 const int maxblocks= 50000;
 
-static const uint64_t FUZZ_TAG = 0x4741542D5A5A5546ULL;
-
 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
-    const uint64_t fuzz_tag = FUZZ_TAG;
     uint32_t it = 0;
     AVFormatContext *avfmt = avformat_alloc_context();
     AVPacket *pkt;
-- 
2.49.0

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Re: [FFmpeg-devel] [PATCH v2 1/4] tools/target_dec_fuzzer: move things to suppress Wdeclaration-after-statement

[Michael Niedermayer]

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Hi Kacper

On Fri, Jun 06, 2025 at 07:20:32PM +0200, Kacper Michajłow wrote:
> To avoid spam in log, each fuzzer is built separately so it's amplified
> a lot.
> 
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  tools/target_dec_fuzzer.c | 31 ++++++++++++++++++-------------
>  1 file changed, 18 insertions(+), 13 deletions(-)

i suggest to remove Wdeclaration-after-statement rather

thx

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

Some Animals are More Equal Than Others. - George Orwell's book Animal Farm

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Re: [FFmpeg-devel] [PATCH v2 2/4] tools/target_dec_fuzzer: suppress Wunused-function

[Michael Niedermayer]

[-- Attachment #1.1: Type: text/plain, Size: 467 bytes --]

On Fri, Jun 06, 2025 at 07:20:33PM +0200, Kacper Michajłow wrote:
> Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> ---
>  tools/target_dec_fuzzer.c | 3 +++
>  1 file changed, 3 insertions(+)

will apply patches 2-4

thx

[...]
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

"Nothing to hide" only works if the folks in power share the values of
you and everyone you know entirely and always will -- Tom Scott


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Re: [FFmpeg-devel] [PATCH v2 1/4] tools/target_dec_fuzzer: move things to suppress Wdeclaration-after-statement

[Kacper Michajlow]

On Fri, 6 Jun 2025 at 23:49, Michael Niedermayer <michael@niedermayer.cc> wrote:
>
> Hi Kacper
>
> On Fri, Jun 06, 2025 at 07:20:32PM +0200, Kacper Michajłow wrote:
> > To avoid spam in log, each fuzzer is built separately so it's amplified
> > a lot.
> >
> > Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
> > ---
> >  tools/target_dec_fuzzer.c | 31 ++++++++++++++++++-------------
> >  1 file changed, 18 insertions(+), 13 deletions(-)
>
> i suggest to remove Wdeclaration-after-statement rather

I see it has recently been removed in configure as
890b8da1ce27fd365eaffefc7efcbadae9f01f2a. So indeed those changes are
not needed anymore.

Thanks for merging the rest of the patches.

- Kacper
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