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
RoundToPow2(size_t v)30 size_t RoundToPow2(size_t v) {
31 uint64_t x = static_cast<uint64_t>(v);
32 if (x < 2)
33 return 2;
34
35 x--;
36 x |= x >> 1;
37 x |= x >> 2;
38 x |= x >> 4;
39 x |= x >> 8;
40 x |= x >> 16;
41 x |= x >> 32;
42 x++;
43 return static_cast<size_t>(x);
44 }
45
FuzzRingBuffer(const uint8_t * data,size_t size)46 int FuzzRingBuffer(const uint8_t* data, size_t size) {
47 if (size <= sizeof(SharedRingBuffer::MetadataPage))
48 return 0;
49
50 auto fd = base::TempFile::CreateUnlinked().ReleaseFD();
51 PERFETTO_CHECK(fd);
52
53 // Use fuzzer input to first fill the SharedRingBuffer::MetadataPage in the
54 // first page, and then put the remainder into the data portion of the ring
55 // buffer (2nd+ pages).
56 size_t payload_size = size - sizeof(SharedRingBuffer::MetadataPage);
57 const uint8_t* payload = data + sizeof(SharedRingBuffer::MetadataPage);
58 size_t payload_size_pages =
59 (payload_size + base::GetSysPageSize() - 1) / base::GetSysPageSize();
60 // Upsize test buffer to be 2^n data pages (precondition of the impl) + 1 page
61 // for the metadata.
62 size_t total_size_pages = 1 + RoundToPow2(payload_size_pages);
63
64 // Clear spinlock field, as otherwise the read will wait indefinitely (it
65 // defaults to indefinite blocking mode).
66 SharedRingBuffer::MetadataPage header = {};
67 memcpy(&header, data, sizeof(header));
68 header.spinlock.locked = false;
69 header.spinlock.poisoned = false;
70
71 PERFETTO_CHECK(ftruncate(*fd, static_cast<off_t>(total_size_pages *
72 base::GetSysPageSize())) ==
73 0);
74 PERFETTO_CHECK(base::WriteAll(*fd, &header, sizeof(header)) != -1);
75 PERFETTO_CHECK(lseek(*fd, base::GetSysPageSize(), SEEK_SET) != -1);
76 PERFETTO_CHECK(base::WriteAll(*fd, payload, payload_size) != -1);
77
78 auto buf = SharedRingBuffer::Attach(std::move(fd));
79 PERFETTO_CHECK(!!buf);
80
81 bool did_read;
82 do {
83 auto read_buf = buf->BeginRead();
84 did_read = bool(read_buf);
85 if (did_read) {
86 volatile uint8_t* v_data = read_buf.data;
87 // Assert we get a reference to valid memory.
88 for (size_t i = 0; i < read_buf.size; ++i)
89 v_data[i] = v_data[i];
90 }
91 buf->EndRead(std::move(read_buf));
92 } while (did_read);
93 return 0;
94 }
95
96 } // namespace
97 } // namespace profiling
98 } // namespace perfetto
99
100 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size);
101
LLVMFuzzerTestOneInput(const uint8_t * data,size_t size)102 extern "C" int LLVMFuzzerTestOneInput(const uint8_t* data, size_t size) {
103 return perfetto::profiling::FuzzRingBuffer(data, size);
104 }
105