1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
|
/*
* Mach Operating System
* Copyright (c) 1991,1990 Carnegie Mellon University
* All Rights Reserved.
*
* Permission to use, copy, modify and distribute this software and its
* documentation is hereby granted, provided that both the copyright
* notice and this permission notice appear in all copies of the
* software, derivative works or modified versions, and any portions
* thereof, and that both notices appear in supporting documentation.
*
* CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
* CONDITION. CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
* ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
*
* Carnegie Mellon requests users of this software to return to
*
* Software Distribution Coordinator or Software.Distribution@CS.CMU.EDU
* School of Computer Science
* Carnegie Mellon University
* Pittsburgh PA 15213-3890
*
* any improvements or extensions that they make and grant Carnegie the
* rights to redistribute these changes.
*/
/*
* Author: David B. Golub, Carnegie Mellon University
* Date: 7/90
*/
#include "ddb.h"
#include "db_sym.h"
#include "swifi.h"
#include "extra.h"
/*
* Multiple symbol tables
*/
#ifndef MAXNOSYMTABS
#define MAXNOSYMTABS 3 /* mach, ux, emulator */
#endif
unsigned int db_maxoff = 0x10000;
unsigned long modAddr = 0;
/* NWT: fault injection routine only.
* figure out start of function address given an address (off) in kernel text.
* name = function name
* value = function address
* d = difference between off and function address
* input is the desired address off and fault type
* returns closest instruction address (if found), NULL otherwise
*/
unsigned long
find_faulty_instr(db_expr_t off, int type, int *instr_len)
{
db_expr_t d;
char *name;
db_expr_t value, cur_value, prev_value = 0;
int verbose=0, found=0;
const char * mod_name = NULL;
unsigned long mod_start;
unsigned long mod_end;
const char * sec_name = NULL;
unsigned long sec_start;
unsigned long sec_end;
const char * sym_name = NULL;
unsigned long sym_start;
unsigned long sym_end;
*instr_len = 0;
if (kallsyms_address_to_symbol(off,
&mod_name, &mod_start, &mod_end,
&sec_name, &sec_start, &sec_end,
&sym_name, &sym_start, &sym_end) == 0) {
return(0);
}
value = (db_expr_t) sym_start;
d = off - sym_start;
name = (char *) sym_name;
if (name == 0) {
value = off;
}
if (value >= DB_SMALL_VALUE_MIN && value <= DB_SMALL_VALUE_MAX) {
printk("0x%x", off);
return 0;
}
if (name == 0 || d >= db_maxoff) {
printk("0x%x", off);
return 0 ;
}
/* 2) backup to start of function (SOF)
* 3) delineate instruction boundaries, find instruction length too.
*/
if(verbose) {
printk("function %s", sym_name);
}
/* 4) skip instructions until we get to our faulty address */
cur_value = value;
while(cur_value < sec_end) {
if(verbose) {
#if 0
// db_printsym(cur_value, DB_STGY_PROC);
// printk(":\t");
#endif
}
prev_value=cur_value;
modAddr=0;
if(verbose) {
#if 0
//cur_value=db_disasm(prev_value, FALSE);
#endif
} else {
cur_value=my_disasm(prev_value, FALSE);
}
/* 4a) bail out if instruction is leave (0xc9) */
if(cur_value-prev_value == 1) {
unsigned char *c;
c=(unsigned char *) prev_value;
if(text_read_ub(c)==0xc9) {
if(verbose) printk("bailing out as we hit a leave\n");
found=0;
break;
}
}
/* 5a) init fault: from SOF, look for movl $X, -Y(%ebp),
* (C645Fxxx or C745Fxxx) and replace with nop.
*/
if(type==INIT_FAULT) {
unsigned char *c;
c=(unsigned char *) prev_value;
if(*c==0x66 || *c==0x67)
c++; /* override prefix */
if(*c==0xC6 || *c==0xC7)
c++; /* movb or movl imm */
else
continue;
if(*c==0x45)
c++; /* [ebp] */
else
continue;
if(*c & 0x80)
found=1; /* negative displacement */
else
continue;
found=1;
break;
} else if(type==NOP_FAULT || type==STOP_FAULT) {
/* 5b) nop*: replace instruction with nop */
if(cur_value> off) {
found=1;
break;
}
} else if(type==DST_FAULT || type==SRC_FAULT) {
/* 5c) dst/src: flip bits in mod/rm, sib, disp or imm fields */
if(cur_value>off && (cur_value-prev_value) > 1) {
found=1;
break;
}
} else if(type==BRANCH_FAULT || type==LOOP_FAULT) {
/* 5e) brc*: search forward utnil we hit a Jxx or rep (F3 or F2).
* replace instr with nop.
*/
unsigned char *c;
c=(unsigned char *) prev_value;
/* look for repX prefix */
if(text_read_ub(c)==0xf3 || text_read_ub(c)==0xf2) {
if(verbose)
printk("found repX prefix\n");
/* take out repX prefix only */
found=1;
cur_value=prev_value+1;
break;
} else if( (text_read_ub(c)&0xf0)==0x70 ||
(text_read_ub(c)>=0xe0 && text_read_ub(c)<=0xe2) ) {
/* look for jXX 8 (7X), loop,jcx (e0-3), jXX 16/32 (0f 8X) */
found=1;
if(verbose)
printk("found jXX rel8, loop or jcx\n");
break;
} else if(text_read_ub(c)==0x66 ||
text_read_ub(c)==0x67) { /* override prefix */
c++;
} else if(text_read_ub(c++)==0xf && (text_read_ub(c)&0xf0)==0x80 ) {
found=1; /* 0x0f 0x8X */
if(verbose) printk("found branch!\n");
break;
}
} else if(type==PTR_FAULT) {
/* 5f) ptr: if instruction has regmodrm byte (i_has_modrm),
* and mod field has address ([eyy]dispxx), eyy!=ebp
* flip 1 bit in lower byte (0x0f) or any bit in following
* bytes (sib, imm or disp).
*/
if(cur_value>off && modAddr) {
unsigned char *c;
c=(unsigned char *) modAddr;
if( text_read_ub(c)>0x3f && text_read_ub(c)<0xc0 &&
(text_read_ub(c)&7)!=5 ) {
found=1;
break;
}
}
} else if(type==INTERFACE_FAULT) {
/* 5f) i/f: look for movl XX(ebp), reg or movb XX(ebp), reg,
* where XX is positive. replace instr with nop.
* movl=0x8a, movb=0x8b, mod=01XXX101 (disp8[ebp]), disp>0
*/
unsigned char *c;
c=(unsigned char *) prev_value;
if( text_read_ub(c)==0x8a || text_read_ub(c)==0x8b) {
c++;
if( ((text_read_ub(c++))&0xc7)==0x45 && (text_read_ub(c)&0x80)==0 ) {
/* 75% chance that we'll choose the next arg */
if(random()&0x3) {
found=1;
break;
} else {
if(verbose) printk("skipped...\n");
}
}
}
}else if(type==IRQ_FAULT) {
/* 5g) i/f: look for push reg or offset(reg) / popf,
* where XX is positive. replace instr with nop.
* movl=0x8a, movb=0x8b, mod=01XXX101 (disp8[ebp]), disp>0
*/
unsigned char *c;
c=(unsigned char *) prev_value;
if (((text_read_ub(c) & 0xf8) == 0x50) ||
(text_read_ub(c) == 0xff)) {
if (text_read_ub(c) == 0xff) {
c++;
#if 0
//
// Look for push x(ebp)
#endif
if ((text_read_ub(c) & 0x78) != 0x70) {
continue;
}
/*
// Skip the offset
*/
c++;
}
c++;
if (text_read_ub(c) == 0x9d) {
/*
// Increment cur_value to include the
// popf instruction
*/
cur_value++;
found = 1;
break;
}
}
}
}
/* if we're doing nop fault, then we're done.
*/
if(found) {
*instr_len=cur_value-prev_value;
off=prev_value;
if(verbose) {
printk("%s", name);
if (d) printk("+0x%x", d);
printk(" @ %x, ", value);
printk("instr @ %x, len=%d, ", off, *instr_len);
}
return off;
} else {
if(verbose) printk("cannot locate instruction in function\n");
*instr_len=0;
return 0;
}
}
|
