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
20 #include "perfetto/base/file_utils.h"
21 #include "perfetto/base/temp_file.h"
22 #include "src/profiling/memory/shared_ring_buffer.h"
23
24 namespace perfetto {
25 namespace profiling {
26 namespace {
27
28 struct FuzzingInputHeader {
29 size_t write_size;
30 SharedRingBuffer::MetadataPage metadata_page;
31 };
32
RoundToPow2(size_t v)33 size_t RoundToPow2(size_t v) {
34 uint64_t x = static_cast<uint64_t>(v);
35 if (x < 2)
36 return 2;
37
38 x--;
39 x |= x >> 1;
40 x |= x >> 2;
41 x |= x >> 4;
42 x |= x >> 8;
43 x |= x >> 16;
44 x |= x >> 32;
45 x++;
46 return static_cast<size_t>(x);
47 }
48
FuzzRingBufferWrite(const uint8_t * data,size_t size)49 int FuzzRingBufferWrite(const uint8_t* data, size_t size) {
50 if (size <= sizeof(FuzzingInputHeader))
51 return 0;
52
53 auto fd = base::TempFile::CreateUnlinked().ReleaseFD();
54 PERFETTO_CHECK(fd);
55
56 // Prefill shared buffer with fuzzer input, then attempt to write.
57 // TODO(fmayer): Do we actually need to fill the buffer with payload, or
58 // should we only fuzz the metadata?
59 size_t payload_size = size - sizeof(FuzzingInputHeader);
60 const uint8_t* payload = data + sizeof(FuzzingInputHeader);
61 size_t payload_size_pages =
62 (payload_size + base::kPageSize - 1) / base::kPageSize;
63 // Upsize test buffer to be 2^n data pages (precondition of the impl) + 1 page
64 // for the metadata.
65 size_t total_size_pages = 1 + RoundToPow2(payload_size_pages);
66
67 // Clear spinlock field, as otherwise we will fail acquiring the lock below.
68 FuzzingInputHeader header = {};
69 memcpy(&header, data, sizeof(header));
70 SharedRingBuffer::MetadataPage& metadata_page = header.metadata_page;
71 metadata_page.spinlock = 0;
72
73 PERFETTO_CHECK(ftruncate(*fd, static_cast<off_t>(total_size_pages *
74 base::kPageSize)) == 0);
75 PERFETTO_CHECK(base::WriteAll(*fd, &metadata_page, sizeof(metadata_page)) !=
76 -1);
77 PERFETTO_CHECK(lseek(*fd, base::kPageSize, SEEK_SET) != -1);
78 PERFETTO_CHECK(base::WriteAll(*fd, payload, payload_size) != -1);
79
80 auto buf = SharedRingBuffer::Attach(std::move(fd));
81 PERFETTO_CHECK(!!buf);
82
83 SharedRingBuffer::Buffer write_buf;
84 {
85 auto lock = buf->AcquireLock(ScopedSpinlock::Mode::Try);
86 PERFETTO_CHECK(lock.locked());
87 write_buf = buf->BeginWrite(lock, header.write_size);
88 }
89 if (!write_buf)
90 return 0;
91
92 memset(write_buf.data, '\0', write_buf.size);
93 buf->EndWrite(std::move(write_buf));
94 return 0;
95 }
96
97 } // namespace
98 } // namespace profiling
99 } // namespace perfetto
100
101 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
102
LLVMFuzzerTestOneInput(const uint8_t * data,size_t size)103 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
104 return perfetto::profiling::FuzzRingBufferWrite(data, size);
105 }
106