skia2/fuzz/FuzzSkDescriptor.cpp
Herb Derby 35c64f6723 Only checksum and query a valid descriptor
Bug: oss-fuzz:19549

Change-Id: I941470cfa31c46b3e92cf53877efd2da8d181c01
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/260896
Commit-Queue: Herb Derby <herb@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>
2019-12-18 20:16:51 +00:00

78 lines
2.2 KiB
C++

/*
* Copyright 2019 Google, LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "fuzz/Fuzz.h"
#include "src/core/SkDescriptor.h"
#include "src/core/SkScalerContext.h"
DEF_FUZZ(SkDescriptor, fuzz) {
int32_t numEntries;
fuzz->next(&numEntries);
// Limit this to keep the fuzz operations fast.
if (numEntries < 0 || numEntries > 300) {
return;
}
size_t overhead = SkDescriptor::ComputeOverhead(numEntries);
size_t data;
fuzz->nextRange(&data, 0, 500);
auto desc = SkDescriptor::Alloc(overhead + data);
for (int32_t i = 0; i<numEntries && !fuzz->exhausted(); i++) {
uint32_t tag;
fuzz->next(&tag);
// Valid use of the API requires that tag is truthy and that
// the length is aligned to 4. If the fuzzed data doesn't conform,
// return to signal that this is "boring" data.
if (!tag) {
return;
}
size_t length;
fuzz->next(&length);
if (SkAlign4(length) != length) {
return;
}
uint8_t choice;
fuzz->nextRange(&choice, 0, 1);
switch(choice) {
case 0: { // use SkScalerContextRec
SkScalerContextRec rec;
fuzz->next(&rec);
desc->addEntry(tag, sizeof(rec), &rec);
break;
}
case 1: { // use arbitrary data
if (fuzz->remaining() < length) {
// Can't initialize all that we requested, so bail out.
return;
}
uint8_t* bytes = new uint8_t[length];
fuzz->nextN(bytes, length);
desc->addEntry(tag, length, bytes);
delete[] bytes;
break;
}
default: {
SK_ABORT("Did you update the range in FuzzSkDescriptor?");
}
}
}
// Exercise the API to make sure we don't step out of bounds, etc.
if (desc->isValid()) {
desc->computeChecksum();
uint32_t tagToFind;
fuzz->next(&tagToFind);
uint32_t ignore;
desc->findEntry(tagToFind, &ignore);
}
}