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Fix uninitialized / NULL pointer use in dwarf_parser #103

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Fix uninitialized / NULL pointer use in dwarf_parser #103

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106 changes: 72 additions & 34 deletions src/dwarf_parser.cc
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -200,12 +200,12 @@ void DwarfParser::traverse_module(Dwfl_Module *mod, Dwarf *dw, bool want_type) {
}
}

Dwarf_Die DwarfParser::find_param(Dwarf_Die *func, string symbol) {
Dwarf_Die vardie;

dwarf_getscopevar(func, 1, symbol.c_str(), 0, NULL, 0, 0, &vardie);

return vardie;
bool DwarfParser::find_param(Dwarf_Die *func, string symbol,
Dwarf_Die &vardie) {
// dwarf_getscopevar: returns a non-negative scope index on success, -1 on
// error or -2 when no matching variable exists. On failure it leaves
// vardie untouched, so the caller must not use it.
return dwarf_getscopevar(func, 1, symbol.c_str(), 0, NULL, 0, 0, &vardie) >= 0;
}

Dwarf_Attribute *DwarfParser::find_func_frame_base(
Expand All @@ -217,27 +217,31 @@ Dwarf_Attribute *DwarfParser::find_func_frame_base(
return fb_attr;
}

VarLocation DwarfParser::translate_param_location(Dwarf_Die *func,
string symbol, Dwarf_Addr pc,
Dwarf_Die &vardie) {
vardie = find_param(func, symbol);
Dwarf_Attribute fb_attr_mem;
Dwarf_Attribute *fb_attr = find_func_frame_base(func, &fb_attr_mem);
bool DwarfParser::translate_param_location(Dwarf_Die *func, string symbol,
Dwarf_Addr pc, Dwarf_Die &vardie,
VarLocation &varloc) {
if (!find_param(func, symbol, vardie)) {
cerr << "Couldn't find parameter " << symbol << endl;
return false;
}

// Assume the vardie must has a DW_AT_location
Dwarf_Attribute loc_attr;
dwarf_attr_integrate(&vardie, DW_AT_location, &loc_attr);
if (dwarf_attr_integrate(&vardie, DW_AT_location, &loc_attr) == NULL) {
cerr << "Parameter " << symbol << " has no DW_AT_location" << endl;
return false;
}

Dwarf_Op *expr;
size_t len;
int r = dwarf_getlocation_addr(&loc_attr, pc, &expr, &len, 1);
if (r != 1 || len <= 0) {
if (r != 1 || len == 0) {
cerr << "Get param location expr failed for symbol " << symbol << endl;
return false;
}

VarLocation varloc;
translate_expr(fb_attr, expr, pc, varloc);
return varloc;
Dwarf_Attribute fb_attr_mem;
Dwarf_Attribute *fb_attr = find_func_frame_base(func, &fb_attr_mem);
return translate_expr(fb_attr, expr, pc, varloc);
}

bool DwarfParser::find_prologue(Dwarf_Die *func, Dwarf_Addr &pc) {
Expand Down Expand Up @@ -307,20 +311,20 @@ Dwarf_Die * DwarfParser::dwarf_attr_die(Dwarf_Die *die, unsigned int attr_flag,
return NULL;
}

void DwarfParser::find_class_member(Dwarf_Die *vardie, Dwarf_Die *typedie,
bool DwarfParser::find_class_member(Dwarf_Die *vardie, Dwarf_Die *typedie,
string member, Dwarf_Attribute *attr) {
// TODO deal with inheritance later

std::queue<Dwarf_Die> die_queue;
die_queue.push(*typedie);
bool found = false;
while (!die_queue.empty()) {
bool found = false;
Dwarf_Die die;
int r = dwarf_child(&die_queue.front(), &die);
if (r != 0) {
cerr << "the class " << dwarf_diename(typedie)
<< " has no children, unexpected and exit" << endl;
return;
return false;
Comment on lines 325 to +327
}
do {
int tag = dwarf_tag(&die);
Expand All @@ -345,15 +349,21 @@ void DwarfParser::find_class_member(Dwarf_Die *vardie, Dwarf_Die *typedie,

} while (dwarf_siblingof(&die, &die) == 0);
die_queue.pop();
if (found)
if (found)
break;
}

if (!found) {
cerr << "couldn't find member " << member << endl;
return false;
}
if (dwarf_hasattr_integrate(vardie, DW_AT_data_member_location)) {
dwarf_attr_integrate(vardie, DW_AT_data_member_location, attr);
} else if (dwarf_hasattr_integrate(vardie, DW_AT_data_bit_offset)) {
// TODO deal with bit member
return true;
}
// DW_AT_data_bit_offset (bitfield) is not handled yet; report failure
// instead of leaving attr unset for the caller to dereference.
return false;
}

void DwarfParser::translate_fields(Dwarf_Die *vardie, Dwarf_Die *typedie,
Expand Down Expand Up @@ -404,15 +414,21 @@ void DwarfParser::translate_fields(Dwarf_Die *vardie, Dwarf_Die *typedie,
*typedie = *tmpdie;
}
Dwarf_Attribute attr;
find_class_member(vardie, typedie, fields[i], &attr);
if (!find_class_member(vardie, typedie, fields[i], &attr)) {
clog << "failed to find member location for " << fields[i] << endl;
return;
}
Comment on lines +417 to +420
Dwarf_Op *expr;
size_t len;
if (dwarf_getlocation_addr(&attr, pc, &expr, &len, 1) != 1) {
if (dwarf_getlocation_addr(&attr, pc, &expr, &len, 1) != 1 || len == 0) {
clog << "failed to get location of attr for " << fields[i] << endl;
return;
}
VarLocation varloc;
translate_expr(NULL, expr, pc, varloc);
if (!translate_expr(NULL, expr, pc, varloc)) {
clog << "failed to translate location of " << fields[i] << endl;
return;
}
Comment thread
xtrusia marked this conversation as resolved.
res[i].offset = varloc.offset;

dwarf_die_type(vardie, typedie);
Expand Down Expand Up @@ -538,7 +554,14 @@ static int handle_function(Dwarf_Die *die, void *data) {
for (int i = 0; i < (int)arr.size(); ++i) {
string varname = arr[i][0];
Dwarf_Die vardie, typedie;
VarLocation varloc = dp->translate_param_location(die, varname, pc, vardie);
VarLocation varloc;
if (!dp->translate_param_location(die, varname, pc, vardie, varloc)) {
cerr << "Skip probe on " << fullname << ": parameter " << varname
<< " unresolved" << endl;
func2pc.erase(fullname);
func2vf.erase(fullname);
return 0;
}
//printf("var %s location : register %d, offset %d, stack %d\n",
//varname.c_str(), varloc.reg, varloc.offset, varloc.stack);
vf[i].varloc = varloc;
Expand All @@ -555,8 +578,12 @@ static int handle_function(Dwarf_Die *die, void *data) {
return 0;
}

void DwarfParser::translate_expr(Dwarf_Attribute *fb_attr, Dwarf_Op *expr,
bool DwarfParser::translate_expr(Dwarf_Attribute *fb_attr, Dwarf_Op *expr,
Dwarf_Addr pc, VarLocation &varloc) {
if (expr == NULL) {
cerr << "translate_expr: null location expression" << endl;
return false;
}
int atom = expr->atom;

// TODO can put a debug message to print the atom's name in string
Expand Down Expand Up @@ -608,14 +635,19 @@ void DwarfParser::translate_expr(Dwarf_Attribute *fb_attr, Dwarf_Op *expr,
break;

case DW_OP_fbreg: {
if (fb_attr == NULL) {
cerr << "translate_expr: DW_OP_fbreg with no frame base" << endl;
return false;
}
Dwarf_Op *fb_expr;
size_t fb_exprlen;
int res = dwarf_getlocation_addr(fb_attr, pc, &fb_expr, &fb_exprlen, 1);
if (res != 1) {
if (res != 1 || fb_exprlen == 0) {
cerr << "translate_expr get fb_expr failed" << endl;
return false;
}

translate_expr(fb_attr, fb_expr, pc, varloc);
if (!translate_expr(fb_attr, fb_expr, pc, varloc)) return false;
varloc.offset += expr->number;
varloc.stack = true;
} break;
Expand All @@ -633,16 +665,21 @@ void DwarfParser::translate_expr(Dwarf_Attribute *fb_attr, Dwarf_Op *expr,
}
}

if (cfa_ops == NULL) {
if (cfa_ops == NULL && cfi_eh != NULL) {
if (dwarf_cfi_addrframe(cfi_eh, pc, &frame) == 0) {
dwarf_frame_cfa(frame, &cfa_ops, &cfa_nops);
} else {
cerr << "dwarf_frame_cfa add eh frame failed" << endl;
}
}

translate_expr(fb_attr, cfa_ops, pc, varloc);
} break;
if (cfa_ops == NULL) {
cerr << "translate_expr: could not resolve call frame CFA" << endl;
return false;
}

return translate_expr(fb_attr, cfa_ops, pc, varloc);
}
case DW_OP_reg0 ... DW_OP_reg31:
varloc.reg = expr->atom - DW_OP_reg0;
break;
Expand All @@ -654,6 +691,7 @@ void DwarfParser::translate_expr(Dwarf_Attribute *fb_attr, Dwarf_Op *expr,
default:
break;
}
return true;
Comment on lines 691 to +694
}

Dwfl *DwarfParser::create_dwfl(int fd, const char *fname) {
Expand Down
10 changes: 5 additions & 5 deletions src/dwarf_parser.h
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Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -70,20 +70,20 @@ class DwarfParser {
const char *cache_type_prefix(Dwarf_Die *);
int iterate_types_in_cu(mod_cu_type_cache_t &, Dwarf_Die *);
void traverse_module(Dwfl_Module *, Dwarf *, bool);
Dwarf_Die find_param(Dwarf_Die *, std::string);
bool find_param(Dwarf_Die *, std::string, Dwarf_Die &);
Dwarf_Attribute *find_func_frame_base(Dwarf_Die *, Dwarf_Attribute *);
VarLocation translate_param_location(Dwarf_Die *, std::string, Dwarf_Addr,
Dwarf_Die &);
bool translate_param_location(Dwarf_Die *, std::string, Dwarf_Addr,
Dwarf_Die &, VarLocation &);
bool func_entrypc(Dwarf_Die *, Dwarf_Addr *);
bool find_prologue(Dwarf_Die *func, Dwarf_Addr &pc);
void dwarf_die_type(Dwarf_Die *, Dwarf_Die *);
void find_class_member(Dwarf_Die *, Dwarf_Die *, std::string,
bool find_class_member(Dwarf_Die *, Dwarf_Die *, std::string,
Dwarf_Attribute *);
void translate_fields(Dwarf_Die *, Dwarf_Die *, Dwarf_Addr,
std::vector<std::string>, std::vector<Field> &);
bool filter_func(std::string);
bool filter_cu(std::string);
void translate_expr(Dwarf_Attribute *, Dwarf_Op *, Dwarf_Addr, VarLocation &);
bool translate_expr(Dwarf_Attribute *, Dwarf_Op *, Dwarf_Addr, VarLocation &);
Dwfl *create_dwfl(int, const char *);
std::string special_inlined_function_scope(const char *);
Dwarf_Die * dwarf_attr_die(Dwarf_Die*, unsigned int, Dwarf_Die*);
Expand Down
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