[FFmpeg-cvslog] avcodec/eac3dec: avoid float noise in fixed mode addition to overflow
Michael Niedermayer
git at videolan.org
Fri May 26 19:20:04 EEST 2023
ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Fri Jan 6 23:36:12 2023 +0100| [ee9cec25662a8b15f7bb8e01eef0f617f14d4e8f] | committer: Michael Niedermayer
avcodec/eac3dec: avoid float noise in fixed mode addition to overflow
Fixes: 2.28595e+09 is outside the range of representable values of type 'int'
Fixes: 54644/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AC3_FIXED_fuzzer-4816961584627712
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 2f48d227c153fa6f0a2156f3e8d18ea1bfedf18d)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=ee9cec25662a8b15f7bb8e01eef0f617f14d4e8f
---
libavcodec/ac3.h | 2 ++
libavcodec/eac3dec.c | 4 +++-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/libavcodec/ac3.h b/libavcodec/ac3.h
index f8f6a81f45..9737337806 100644
--- a/libavcodec/ac3.h
+++ b/libavcodec/ac3.h
@@ -75,6 +75,7 @@
#define AC3_DYNAMIC_RANGE1 0
typedef int INTFLOAT;
+typedef unsigned int UINTFLOAT;
typedef int16_t SHORTFLOAT;
#else /* USE_FIXED */
@@ -94,6 +95,7 @@ typedef int16_t SHORTFLOAT;
#define AC3_DYNAMIC_RANGE1 1.0f
typedef float INTFLOAT;
+typedef float UINTFLOAT;
typedef float SHORTFLOAT;
#endif /* USE_FIXED */
diff --git a/libavcodec/eac3dec.c b/libavcodec/eac3dec.c
index 73067ded9d..7558d787fb 100644
--- a/libavcodec/eac3dec.c
+++ b/libavcodec/eac3dec.c
@@ -145,9 +145,11 @@ static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
// spx_noise_blend and spx_signal_blend are both FP.23
nscale *= 1.0 / (1<<23);
sscale *= 1.0 / (1<<23);
+ if (nscale < -1.0)
+ nscale = -1.0;
#endif
for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
- float noise = nscale * (int32_t)av_lfg_get(&s->dith_state);
+ UINTFLOAT noise = (INTFLOAT)(nscale * (int32_t)av_lfg_get(&s->dith_state));
s->transform_coeffs[ch][bin] *= sscale;
s->transform_coeffs[ch][bin++] += noise;
}
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