1 #include <stdio.h>
2 #include <assert.h>
3
4 #include "zbuild.h"
5 #ifdef ZLIB_COMPAT
6 # include "zlib.h"
7 #else
8 # include "zlib-ng.h"
9 #endif
10
11 static const uint8_t *data;
12 static size_t dataLen;
13
check_compress_level(uint8_t * compr,z_size_t comprLen,uint8_t * uncompr,z_size_t uncomprLen,int level)14 static void check_compress_level(uint8_t *compr, z_size_t comprLen,
15 uint8_t *uncompr, z_size_t uncomprLen,
16 int level) {
17 PREFIX(compress2)(compr, &comprLen, data, dataLen, level);
18 PREFIX(uncompress)(uncompr, &uncomprLen, compr, comprLen);
19
20 /* Make sure compress + uncompress gives back the input data. */
21 assert(dataLen == uncomprLen);
22 assert(0 == memcmp(data, uncompr, dataLen));
23 }
24
25 #define put_byte(s, i, c) {s[i] = (unsigned char)(c);}
26
write_zlib_header(uint8_t * s)27 static void write_zlib_header(uint8_t *s) {
28 unsigned level_flags = 0; /* compression level (0..3) */
29 unsigned w_bits = 8; /* window size log2(w_size) (8..16) */
30 unsigned int header = (Z_DEFLATED + ((w_bits-8)<<4)) << 8;
31 header |= (level_flags << 6);
32
33 header += 31 - (header % 31);
34
35 /* s is guaranteed to be longer than 2 bytes. */
36 put_byte(s, 0, (header >> 8));
37 put_byte(s, 1, (header & 0xff));
38 }
39
check_decompress(uint8_t * compr,size_t comprLen)40 static void check_decompress(uint8_t *compr, size_t comprLen) {
41 /* We need to write a valid zlib header of size two bytes. Copy the input data
42 in a larger buffer. Do not modify the input data to avoid libFuzzer error:
43 fuzz target overwrites its const input. */
44 size_t copyLen = dataLen + 2;
45 uint8_t *copy = (uint8_t *)malloc(copyLen);
46 memcpy(copy + 2, data, dataLen);
47 write_zlib_header(copy);
48
49 PREFIX(uncompress)(compr, &comprLen, copy, copyLen);
50 free(copy);
51 }
52
LLVMFuzzerTestOneInput(const uint8_t * d,size_t size)53 int LLVMFuzzerTestOneInput(const uint8_t *d, size_t size) {
54 /* compressBound does not provide enough space for low compression levels. */
55 z_size_t comprLen = 100 + 2 * PREFIX(compressBound)(size);
56 z_size_t uncomprLen = (z_size_t)size;
57 uint8_t *compr, *uncompr;
58
59 /* Discard inputs larger than 1Mb. */
60 static size_t kMaxSize = 1024 * 1024;
61
62 if (size < 1 || size > kMaxSize)
63 return 0;
64
65 data = d;
66 dataLen = size;
67 compr = (uint8_t *)calloc(1, comprLen);
68 uncompr = (uint8_t *)calloc(1, uncomprLen);
69
70 check_compress_level(compr, comprLen, uncompr, uncomprLen, 1);
71 check_compress_level(compr, comprLen, uncompr, uncomprLen, 3);
72 check_compress_level(compr, comprLen, uncompr, uncomprLen, 6);
73 check_compress_level(compr, comprLen, uncompr, uncomprLen, 7);
74
75 check_decompress(compr, comprLen);
76
77 free(compr);
78 free(uncompr);
79
80 /* This function must return 0. */
81 return 0;
82 }
83