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tools/target_dec_fuzzer: Limit number off all pixels decoded 

This should reduces the number of uninteresting timeouts encountered

A single threshold for all codecs did not work

Fixes: 13979/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_QTRLE_fuzzer-5629872380051456 (14sec -> 4sec)
Fixes: 14709/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_GDV_fuzzer-5704215281795072 (179sec -> 7sec)
Fixes: 16296/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_HNM4_VIDEO_fuzzer-5756304521428992 (108sec -> 9sec)
Fixes: 15620/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_GIF_fuzzer-5657214435459072 (26sec -> 26ms)

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2019-07-31 10:11:15 +02:00
parent cd460f4da0
commit 9e0e9a5f36
1 changed files with 17 additions and 1 deletions
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18
tools/target_dec_fuzzer.c
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@ -128,6 +128,8 @@ static void FDBPrepare(FuzzDataBuffer *FDB, AVPacket *dst, const uint8_t *data,
// Ensure we don't loop forever
const uint32_t maxiteration = 8096;
const uint64_t maxpixels_per_frame = 4096 * 4096;
uint64_t maxpixels;
static const uint64_t FUZZ_TAG = 0x4741542D5A5A5546ULL;
@ -165,13 +167,24 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
case AVMEDIA_TYPE_VIDEO : decode_handler = avcodec_decode_video2; break;
case AVMEDIA_TYPE_SUBTITLE: decode_handler = subtitle_handler ; break;
}
maxpixels = maxpixels_per_frame * maxiteration;
switch (c->id) {
// Allows a small input to generate gigantic output
case AV_CODEC_ID_QTRLE: maxpixels /= 16;
case AV_CODEC_ID_GIF: maxpixels /= 16;
// Performs slow frame rescaling in C
case AV_CODEC_ID_GDV: maxpixels /= 256;
// Postprocessing in C
case AV_CODEC_ID_HNM4_VIDEO:maxpixels /= 128;
}
AVCodecContext* ctx = avcodec_alloc_context3(NULL);
AVCodecContext* parser_avctx = avcodec_alloc_context3(NULL);
if (!ctx || !parser_avctx)
error("Failed memory allocation");
ctx->max_pixels = 4096 * 4096; //To reduce false positive OOM and hangs
ctx->max_pixels = maxpixels_per_frame; //To reduce false positive OOM and hangs
if (size > 1024) {
GetByteContext gbc;
@ -260,6 +273,8 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
ec_pixels += ctx->width * ctx->height;
if (it > 20 || ec_pixels > 4 * ctx->max_pixels)
ctx->error_concealment = 0;
if (ec_pixels > maxpixels)
goto maximums_reached;
if (ret <= 0 || ret > avpkt.size)
break;
@ -270,6 +285,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
}
}
}
maximums_reached:
av_init_packet(&avpkt);
avpkt.data = NULL;