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[FFmpeg-devel,2/3] avcodec/pngdec: Check amount decoded

Message ID 20200128193217.30405-2-michael@niedermayer.cc
State Accepted
Headers show
Series [FFmpeg-devel,1/3] avcodec/apedec: Fix integer overflows in predictor_decode_mono_3950()
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Context Check Description
andriy/ffmpeg-patchwork pending
andriy/ffmpeg-patchwork success Applied patch
andriy/ffmpeg-patchwork success Configure finished
andriy/ffmpeg-patchwork success Make finished
andriy/ffmpeg-patchwork success Make fate finished

Commit Message

Michael Niedermayer Jan. 28, 2020, 7:32 p.m. UTC 
Fixes: Timeout (70sec -> 243ms)
Fixes: 16097/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5664690889293824
Fixes: 16927/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5170612070252544
Fixes: 16927/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5706325622784000
Fixes: 18705/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_APNG_fuzzer-5650989302677504

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/pngdec.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
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Patch

diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index d37dabcc4d..3ce980fc15 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -320,6 +320,15 @@  static void deloco_ ## NAME(TYPE *dst, int size, int alpha) \
 YUV2RGB(rgb8, uint8_t)
 YUV2RGB(rgb16, uint16_t)
 
+static int percent_missing(PNGDecContext *s)
+{
+    if (s->interlace_type) {
+        return 100 - 100 * s->pass / (NB_PASSES - 1);
+    } else {
+        return 100 - 100 * s->y / s->cur_h;
+    }
+}
+
 /* process exactly one decompressed row */
 static void png_handle_row(PNGDecContext *s)
 {
@@ -1354,6 +1363,9 @@  exit_loop:
         return 0;
     }
 
+    if (percent_missing(s) > avctx->discard_damaged_percentage)
+        return AVERROR_INVALIDDATA;
+
     if (s->bits_per_pixel <= 4)
         handle_small_bpp(s, p);