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advanced_api_fuzzer: add extreme config value coverage

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this enables cases that might trigger overflows, but increases the risk
of OOM and timeouts

Bug: chromium:1196850
Change-Id: I317b5109525646731e762faa3c34ed28a27595dc
This commit is contained in:
James Zern 2021-06-07 18:59:44 -07:00
parent 72fe52f623
commit b60d460318
1 changed files with 48 additions and 31 deletions
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79
tests/fuzzer/advanced_api_fuzzer.c
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@ -14,10 +14,13 @@
//
////////////////////////////////////////////////////////////////////////////////
#include <string.h>
#include "./fuzz_utils.h"
#include "webp/decode.h"
int LLVMFuzzerTestOneInput(const uint8_t* const data, size_t size) {
int i;
WebPDecoderConfig config;
if (!WebPInitDecoderConfig(&config)) return 0;
if (WebPGetFeatures(data, size, &config.input) != VP8_STATUS_OK) return 0;
@ -59,39 +62,53 @@ int LLVMFuzzerTestOneInput(const uint8_t* const data, size_t size) {
config.output.colorspace = (WEBP_CSP_MODE)(value % MODE_LAST);
#endif // WEBP_REDUCE_CSP
if (size % 3) {
// Decodes incrementally in chunks of increasing size.
WebPIDecoder* idec = WebPIDecode(NULL, 0, &config);
if (!idec) return 0;
VP8StatusCode status;
if (size & 8) {
size_t available_size = value + 1;
while (1) {
if (available_size > size) available_size = size;
status = WebPIUpdate(idec, data, available_size);
if (status != VP8_STATUS_SUSPENDED || available_size == size) break;
available_size *= 2;
}
} else {
// WebPIAppend expects new data and its size with each call.
// Implemented here by simply advancing the pointer into data.
const uint8_t* new_data = data;
size_t new_size = value + 1;
while (1) {
if (new_data + new_size > data + size) {
new_size = data + size - new_data;
}
status = WebPIAppend(idec, new_data, new_size);
if (status != VP8_STATUS_SUSPENDED || new_size == 0) break;
new_data += new_size;
new_size *= 2;
for (i = 0; i < 2; ++i) {
if (i == 1) {
// Use the bitstream data to generate extreme ranges for the options. An
// alternative approach would be to use a custom corpus containing webp
// files prepended with sizeof(config.options) zeroes to allow the fuzzer
// to modify these independently.
const int data_offset = 50;
if (size > data_offset + sizeof(config.options)) {
memcpy(&config.options, data + data_offset, sizeof(config.options));
} else {
break;
}
}
WebPIDelete(idec);
} else {
WebPDecode(data, size, &config);
}
if (size % 3) {
// Decodes incrementally in chunks of increasing size.
WebPIDecoder* idec = WebPIDecode(NULL, 0, &config);
if (!idec) return 0;
VP8StatusCode status;
if (size & 8) {
size_t available_size = value + 1;
while (1) {
if (available_size > size) available_size = size;
status = WebPIUpdate(idec, data, available_size);
if (status != VP8_STATUS_SUSPENDED || available_size == size) break;
available_size *= 2;
}
} else {
// WebPIAppend expects new data and its size with each call.
// Implemented here by simply advancing the pointer into data.
const uint8_t* new_data = data;
size_t new_size = value + 1;
while (1) {
if (new_data + new_size > data + size) {
new_size = data + size - new_data;
}
status = WebPIAppend(idec, new_data, new_size);
if (status != VP8_STATUS_SUSPENDED || new_size == 0) break;
new_data += new_size;
new_size *= 2;
}
}
WebPIDelete(idec);
} else {
WebPDecode(data, size, &config);
}
WebPFreeDecBuffer(&config.output);
WebPFreeDecBuffer(&config.output);
}
return 0;
}