1 /*
2 * Copyright (C) 2019 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <stddef.h>
18 #include <stdint.h>
19 #include <unistd.h>
20
21 #include "perfetto/ext/base/file_utils.h"
22 #include "perfetto/ext/base/temp_file.h"
23 #include "perfetto/ext/base/utils.h"
24 #include "src/profiling/memory/shared_ring_buffer.h"
25
26 namespace perfetto {
27 namespace profiling {
28 namespace {
29
30 struct FuzzingInputHeader {
31 size_t write_size;
32 SharedRingBuffer::MetadataPage metadata_page;
33 };
34
RoundToPow2(size_t v)35 size_t RoundToPow2(size_t v) {
36 uint64_t x = static_cast<uint64_t>(v);
37 if (x < 2)
38 return 2;
39
40 x--;
41 x |= x >> 1;
42 x |= x >> 2;
43 x |= x >> 4;
44 x |= x >> 8;
45 x |= x >> 16;
46 x |= x >> 32;
47 x++;
48 return static_cast<size_t>(x);
49 }
50
FuzzRingBufferWrite(const uint8_t * data,size_t size)51 int FuzzRingBufferWrite(const uint8_t* data, size_t size) {
52 if (size <= sizeof(FuzzingInputHeader))
53 return 0;
54
55 auto fd = base::TempFile::CreateUnlinked().ReleaseFD();
56 PERFETTO_CHECK(fd);
57
58 // Prefill shared buffer with fuzzer input, then attempt to write.
59 // TODO(fmayer): Do we actually need to fill the buffer with payload, or
60 // should we only fuzz the metadata?
61 size_t payload_size = size - sizeof(FuzzingInputHeader);
62 const uint8_t* payload = data + sizeof(FuzzingInputHeader);
63 size_t payload_size_pages =
64 (payload_size + base::GetSysPageSize() - 1) / base::GetSysPageSize();
65 // Upsize test buffer to be 2^n data pages (precondition of the impl) + 1 page
66 // for the metadata.
67 size_t total_size_pages = 1 + RoundToPow2(payload_size_pages);
68
69 // Clear spinlock field, as otherwise we will fail acquiring the lock below.
70 FuzzingInputHeader header = {};
71 memcpy(&header, data, sizeof(header));
72 SharedRingBuffer::MetadataPage& metadata_page = header.metadata_page;
73 metadata_page.spinlock.locked = false;
74 metadata_page.spinlock.poisoned = false;
75
76 PERFETTO_CHECK(ftruncate(*fd, static_cast<off_t>(total_size_pages *
77 base::GetSysPageSize())) ==
78 0);
79 PERFETTO_CHECK(base::WriteAll(*fd, &metadata_page, sizeof(metadata_page)) !=
80 -1);
81 PERFETTO_CHECK(lseek(*fd, base::GetSysPageSize(), SEEK_SET) != -1);
82 PERFETTO_CHECK(base::WriteAll(*fd, payload, payload_size) != -1);
83
84 auto buf = SharedRingBuffer::Attach(std::move(fd));
85 PERFETTO_CHECK(!!buf);
86
87 SharedRingBuffer::Buffer write_buf;
88 {
89 auto lock = buf->AcquireLock(ScopedSpinlock::Mode::Try);
90 PERFETTO_CHECK(lock.locked());
91 write_buf = buf->BeginWrite(lock, header.write_size);
92 }
93 if (!write_buf)
94 return 0;
95
96 memset(write_buf.data, '\0', write_buf.size);
97 buf->EndWrite(std::move(write_buf));
98 return 0;
99 }
100
101 } // namespace
102 } // namespace profiling
103 } // namespace perfetto
104
105 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
106
LLVMFuzzerTestOneInput(const uint8_t * data,size_t size)107 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
108 return perfetto::profiling::FuzzRingBufferWrite(data, size);
109 }
110