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1 /***************************************************************************
2 Fuzzer driver for PCRE2. Given an arbitrary string of bytes and a length, it
3 tries to compile and match it, deriving options from the string itself. If
4 STANDALONE is defined, a main program that calls the driver with the contents
5 of specified files is compiled, and commentary on what is happening is output.
6 If an argument starts with '=' the rest of it it is taken as a literal string
7 rather than a file name. This allows easy testing of short strings.
8 
9 Written by Philip Hazel, October 2016
10 ***************************************************************************/
11 
12 #include <errno.h>
13 #include <stdio.h>
14 #include <stdlib.h>
15 #include <string.h>
16 
17 #define PCRE2_CODE_UNIT_WIDTH 8
18 #include "pcre2.h"
19 
20 #define MAX_MATCH_SIZE 1000
21 
22 #define DFA_WORKSPACE_COUNT 100
23 
24 #define ALLOWED_COMPILE_OPTIONS \
25   (PCRE2_ANCHORED|PCRE2_ALLOW_EMPTY_CLASS|PCRE2_ALT_BSUX|PCRE2_ALT_CIRCUMFLEX| \
26    PCRE2_ALT_VERBNAMES|PCRE2_AUTO_CALLOUT|PCRE2_CASELESS|PCRE2_DOLLAR_ENDONLY| \
27    PCRE2_DOTALL|PCRE2_DUPNAMES|PCRE2_ENDANCHORED|PCRE2_EXTENDED|PCRE2_FIRSTLINE| \
28    PCRE2_MATCH_UNSET_BACKREF|PCRE2_MULTILINE|PCRE2_NEVER_BACKSLASH_C| \
29    PCRE2_NO_AUTO_CAPTURE| \
30    PCRE2_NO_AUTO_POSSESS|PCRE2_NO_DOTSTAR_ANCHOR|PCRE2_NO_START_OPTIMIZE| \
31    PCRE2_UCP|PCRE2_UNGREEDY|PCRE2_USE_OFFSET_LIMIT| \
32    PCRE2_UTF)
33 
34 #define ALLOWED_MATCH_OPTIONS \
35   (PCRE2_ANCHORED|PCRE2_ENDANCHORED|PCRE2_NOTBOL|PCRE2_NOTEOL|PCRE2_NOTEMPTY| \
36    PCRE2_NOTEMPTY_ATSTART|PCRE2_PARTIAL_HARD| \
37    PCRE2_PARTIAL_SOFT|PCRE2_NO_JIT)
38 
39 /* This is the callout function. Its only purpose is to halt matching if there
40 are more than 100 callouts, as one way of stopping too much time being spent on
41 fruitless matches. The callout data is a pointer to the counter. */
42 
callout_function(pcre2_callout_block * cb,void * callout_data)43 static int callout_function(pcre2_callout_block *cb, void *callout_data)
44 {
45 (void)cb;  /* Avoid unused parameter warning */
46 *((uint32_t *)callout_data) += 1;
47 return (*((uint32_t *)callout_data) > 100)? PCRE2_ERROR_CALLOUT : 0;
48 }
49 
50 /* Putting in this apparently unnecessary prototype prevents gcc from giving a
51 "no previous prototype" warning when compiling at high warning level. */
52 
53 int LLVMFuzzerTestOneInput(const unsigned char *, size_t);
54 
55 /* Here's the driving function. */
56 
LLVMFuzzerTestOneInput(const unsigned char * data,size_t size)57 int LLVMFuzzerTestOneInput(const unsigned char *data, size_t size)
58 {
59 uint32_t compile_options;
60 uint32_t match_options;
61 pcre2_match_data *match_data = NULL;
62 pcre2_match_context *match_context = NULL;
63 size_t match_size;
64 int dfa_workspace[DFA_WORKSPACE_COUNT];
65 int r1, r2;
66 int i;
67 
68 if (size < 1) return 0;
69 
70 /* Limiting the length of the subject for matching stops fruitless searches
71 in large trees taking too much time. */
72 
73 match_size = (size > MAX_MATCH_SIZE)? MAX_MATCH_SIZE : size;
74 
75 /* Figure out some options to use. Initialize the random number to ensure
76 repeatability. Ensure that we get a 32-bit unsigned random number for testing
77 options. (RAND_MAX is required to be at least 32767, but is commonly
78 2147483647, which excludes the top bit.) */
79 
80 srand((unsigned int)(data[size/2]));
81 r1 = rand();
82 r2 = rand();
83 
84 /* Ensure that all undefined option bits are zero (waste of time trying them)
85 and also that PCRE2_NO_UTF_CHECK is unset, as there is no guarantee that the
86 input is UTF-8. Also unset PCRE2_NEVER_UTF and PCRE2_NEVER_UCP as there is no
87 reason to disallow UTF and UCP. Force PCRE2_NEVER_BACKSLASH_C to be set because
88 \C in random patterns is highly likely to cause a crash. */
89 
90 compile_options =
91   ((((uint32_t)r1 << 16) | ((uint32_t)r2 & 0xffff)) & ALLOWED_COMPILE_OPTIONS) |
92   PCRE2_NEVER_BACKSLASH_C;
93 
94 match_options =
95   ((((uint32_t)r1 << 16) | ((uint32_t)r2 & 0xffff)) & ALLOWED_MATCH_OPTIONS);
96 
97 /* Discard partial matching if PCRE2_ENDANCHORED is set, because they are not
98 allowed together and just give an immediate error return. */
99 
100 if (((compile_options|match_options) & PCRE2_ENDANCHORED) != 0)
101   match_options &= ~(PCRE2_PARTIAL_HARD|PCRE2_PARTIAL_SOFT);
102 
103 /* Do the compile with and without the options, and after a successful compile,
104 likewise do the match with and without the options. */
105 
106 for (i = 0; i < 2; i++)
107   {
108   uint32_t callout_count;
109   int errorcode;
110   PCRE2_SIZE erroroffset;
111   pcre2_code *code;
112 
113 #ifdef STANDALONE
114   printf("Compile options %.8x never_backslash_c", compile_options);
115   printf("%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s%s\n",
116     ((compile_options & PCRE2_ALT_BSUX) != 0)? ",alt_bsux" : "",
117     ((compile_options & PCRE2_ALT_CIRCUMFLEX) != 0)? ",alt_circumflex" : "",
118     ((compile_options & PCRE2_ALT_VERBNAMES) != 0)? ",alt_verbnames" : "",
119     ((compile_options & PCRE2_ALLOW_EMPTY_CLASS) != 0)? ",allow_empty_class" : "",
120     ((compile_options & PCRE2_ANCHORED) != 0)? ",anchored" : "",
121     ((compile_options & PCRE2_AUTO_CALLOUT) != 0)? ",auto_callout" : "",
122     ((compile_options & PCRE2_CASELESS) != 0)? ",caseless" : "",
123     ((compile_options & PCRE2_DOLLAR_ENDONLY) != 0)? ",dollar_endonly" : "",
124     ((compile_options & PCRE2_DOTALL) != 0)? ",dotall" : "",
125     ((compile_options & PCRE2_DUPNAMES) != 0)? ",dupnames" : "",
126     ((compile_options & PCRE2_ENDANCHORED) != 0)? ",endanchored" : "",
127     ((compile_options & PCRE2_EXTENDED) != 0)? ",extended" : "",
128     ((compile_options & PCRE2_FIRSTLINE) != 0)? ",firstline" : "",
129     ((compile_options & PCRE2_MATCH_UNSET_BACKREF) != 0)? ",match_unset_backref" : "",
130     ((compile_options & PCRE2_MULTILINE) != 0)? ",multiline" : "",
131     ((compile_options & PCRE2_NEVER_UCP) != 0)? ",never_ucp" : "",
132     ((compile_options & PCRE2_NEVER_UTF) != 0)? ",never_utf" : "",
133     ((compile_options & PCRE2_NO_AUTO_CAPTURE) != 0)? ",no_auto_capture" : "",
134     ((compile_options & PCRE2_NO_AUTO_POSSESS) != 0)? ",no_auto_possess" : "",
135     ((compile_options & PCRE2_NO_DOTSTAR_ANCHOR) != 0)? ",no_dotstar_anchor" : "",
136     ((compile_options & PCRE2_NO_UTF_CHECK) != 0)? ",no_utf_check" : "",
137     ((compile_options & PCRE2_NO_START_OPTIMIZE) != 0)? ",no_start_optimize" : "",
138     ((compile_options & PCRE2_UCP) != 0)? ",ucp" : "",
139     ((compile_options & PCRE2_UNGREEDY) != 0)? ",ungreedy" : "",
140     ((compile_options & PCRE2_USE_OFFSET_LIMIT) != 0)? ",use_offset_limit" : "",
141     ((compile_options & PCRE2_UTF) != 0)? ",utf" : "");
142 #endif
143 
144   code = pcre2_compile((PCRE2_SPTR)data, (PCRE2_SIZE)size, compile_options,
145     &errorcode, &erroroffset, NULL);
146 
147   /* Compilation succeeded */
148 
149   if (code != NULL)
150     {
151     int j;
152     uint32_t save_match_options = match_options;
153 
154     /* Create match data and context blocks only when we first need them. Set
155     low match and depth limits to avoid wasting too much searching large
156     pattern trees. Almost all matches are going to fail. */
157 
158     if (match_data == NULL)
159       {
160       match_data = pcre2_match_data_create(32, NULL);
161       if (match_data == NULL)
162         {
163 #ifdef STANDALONE
164         printf("** Failed to create match data block\n");
165 #endif
166         return 0;
167         }
168       }
169 
170     if (match_context == NULL)
171       {
172       match_context = pcre2_match_context_create(NULL);
173       if (match_context == NULL)
174         {
175 #ifdef STANDALONE
176         printf("** Failed to create match context block\n");
177 #endif
178         return 0;
179         }
180       (void)pcre2_set_match_limit(match_context, 100);
181       (void)pcre2_set_depth_limit(match_context, 100);
182       (void)pcre2_set_callout(match_context, callout_function, &callout_count);
183       }
184 
185     /* Match twice, with and without options. */
186 
187     for (j = 0; j < 2; j++)
188       {
189 #ifdef STANDALONE
190       printf("Match options %.8x", match_options);
191       printf("%s%s%s%s%s%s%s%s%s%s\n",
192         ((match_options & PCRE2_ANCHORED) != 0)? ",anchored" : "",
193         ((match_options & PCRE2_ENDANCHORED) != 0)? ",endanchored" : "",
194         ((match_options & PCRE2_NO_JIT) != 0)? ",no_jit" : "",
195         ((match_options & PCRE2_NO_UTF_CHECK) != 0)? ",no_utf_check" : "",
196         ((match_options & PCRE2_NOTBOL) != 0)? ",notbol" : "",
197         ((match_options & PCRE2_NOTEMPTY) != 0)? ",notempty" : "",
198         ((match_options & PCRE2_NOTEMPTY_ATSTART) != 0)? ",notempty_atstart" : "",
199         ((match_options & PCRE2_NOTEOL) != 0)? ",noteol" : "",
200         ((match_options & PCRE2_PARTIAL_HARD) != 0)? ",partial_hard" : "",
201         ((match_options & PCRE2_PARTIAL_SOFT) != 0)? ",partial_soft" : "");
202 #endif
203 
204       callout_count = 0;
205       errorcode = pcre2_match(code, (PCRE2_SPTR)data, (PCRE2_SIZE)match_size, 0,
206         match_options, match_data, match_context);
207 
208 #ifdef STANDALONE
209       if (errorcode >= 0) printf("Match returned %d\n", errorcode); else
210         {
211         unsigned char buffer[256];
212         pcre2_get_error_message(errorcode, buffer, 256);
213         printf("Match failed: error %d: %s\n", errorcode, buffer);
214         }
215 #endif
216 
217       match_options = 0;  /* For second time */
218       }
219 
220     /* Match with DFA twice, with and without options. */
221 
222     match_options = save_match_options & ~PCRE2_NO_JIT;  /* Not valid for DFA */
223 
224     for (j = 0; j < 2; j++)
225       {
226 #ifdef STANDALONE
227       printf("DFA match options %.8x", match_options);
228       printf("%s%s%s%s%s%s%s%s%s\n",
229         ((match_options & PCRE2_ANCHORED) != 0)? ",anchored" : "",
230         ((match_options & PCRE2_ENDANCHORED) != 0)? ",endanchored" : "",
231         ((match_options & PCRE2_NO_UTF_CHECK) != 0)? ",no_utf_check" : "",
232         ((match_options & PCRE2_NOTBOL) != 0)? ",notbol" : "",
233         ((match_options & PCRE2_NOTEMPTY) != 0)? ",notempty" : "",
234         ((match_options & PCRE2_NOTEMPTY_ATSTART) != 0)? ",notempty_atstart" : "",
235         ((match_options & PCRE2_NOTEOL) != 0)? ",noteol" : "",
236         ((match_options & PCRE2_PARTIAL_HARD) != 0)? ",partial_hard" : "",
237         ((match_options & PCRE2_PARTIAL_SOFT) != 0)? ",partial_soft" : "");
238 #endif
239 
240       callout_count = 0;
241       errorcode = pcre2_dfa_match(code, (PCRE2_SPTR)data,
242         (PCRE2_SIZE)match_size, 0, match_options, match_data, match_context,
243         dfa_workspace, DFA_WORKSPACE_COUNT);
244 
245 #ifdef STANDALONE
246       if (errorcode >= 0) printf("Match returned %d\n", errorcode); else
247         {
248         unsigned char buffer[256];
249         pcre2_get_error_message(errorcode, buffer, 256);
250         printf("Match failed: error %d: %s\n", errorcode, buffer);
251         }
252 #endif
253 
254       match_options = 0;  /* For second time */
255       }
256 
257     match_options = save_match_options;  /* Reset for the second compile */
258     pcre2_code_free(code);
259     }
260 
261   /* Compilation failed */
262 
263   else
264     {
265     unsigned char buffer[256];
266     pcre2_get_error_message(errorcode, buffer, 256);
267 #ifdef STANDALONE
268     printf("Error %d at offset %lu: %s\n", errorcode, erroroffset, buffer);
269 #else
270     if (strstr((const char *)buffer, "internal error") != NULL) abort();
271 #endif
272     }
273 
274   compile_options = PCRE2_NEVER_BACKSLASH_C;  /* For second time */
275   }
276 
277 if (match_data != NULL) pcre2_match_data_free(match_data);
278 if (match_context != NULL) pcre2_match_context_free(match_context);
279 
280 return 0;
281 }
282 
283 
284 /* Optional main program.  */
285 
286 #ifdef STANDALONE
main(int argc,char ** argv)287 int main(int argc, char **argv)
288 {
289 int i;
290 
291 if (argc < 2)
292   {
293   printf("** No arguments given\n");
294   return 0;
295   }
296 
297 for (i = 1; i < argc; i++)
298   {
299   size_t filelen;
300   size_t readsize;
301   unsigned char *buffer;
302   FILE *f;
303 
304   /* Handle a literal string. Copy to an exact size buffer so that checks for
305   overrunning work. */
306 
307   if (argv[i][0] == '=')
308     {
309     readsize = strlen(argv[i]) - 1;
310     printf("------ <Literal> ------\n");
311     printf("Length = %lu\n", readsize);
312     printf("%.*s\n", (int)readsize, argv[i]+1);
313     buffer = (unsigned char *)malloc(readsize);
314     if (buffer == NULL)
315       printf("** Failed to allocate %lu bytes of memory\n", readsize);
316     else
317       {
318       memcpy(buffer, argv[i]+1, readsize);
319       LLVMFuzzerTestOneInput(buffer, readsize);
320       free(buffer);
321       }
322     continue;
323     }
324 
325   /* Handle a string given in a file */
326 
327   f = fopen(argv[i], "rb");
328   if (f == NULL)
329     {
330     printf("** Failed to open %s: %s\n", argv[i], strerror(errno));
331     continue;
332     }
333 
334   printf("------ %s ------\n", argv[i]);
335 
336   fseek(f, 0, SEEK_END);
337   filelen = ftell(f);
338   fseek(f, 0, SEEK_SET);
339 
340   buffer = (unsigned char *)malloc(filelen);
341   if (buffer == NULL)
342     {
343     printf("** Failed to allocate %lu bytes of memory\n", filelen);
344     fclose(f);
345     continue;
346     }
347 
348   readsize = fread(buffer, 1, filelen, f);
349   fclose(f);
350 
351   if (readsize != filelen)
352     printf("** File size is %lu but fread() returned %lu\n", filelen, readsize);
353   else
354     {
355     printf("Length = %lu\n", filelen);
356     LLVMFuzzerTestOneInput(buffer, filelen);
357     }
358   free(buffer);
359   }
360 
361 return 0;
362 }
363 #endif  /* STANDALONE */
364 
365 /* End */
366