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Print function name and file location when caught a SIGSEGV

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This commit is contained in:
Kamil Kowalczyk
2025-03-12 14:25:55 +01:00
parent 6a5b07fa93
commit 3b938a06dd
7 changed files with 131 additions and 46 deletions
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36
.debugusrc1.js
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@@ -6,27 +6,27 @@ ler("Test error message");
var offset = "0x0000000000001169"; // dupa(), objdump -d ./test
// Testing...
pf();
ppid();
pplo();
// pf();
// ppid();
// pplo();
baddr(offset);
lsbrk();
lif("1 --------------------------------------------");
dr();
var r14 = gr("r14");
sr("r14", "0x0");
lif("2 --------------------------------------------");
dr();
sr("r14", r14);
lif("3 --------------------------------------------");
dr();
// lif("1 --------------------------------------------");
// dr();
// var r14 = gr("r14");
// sr("r14", "0x0");
// lif("2 --------------------------------------------");
// dr();
// sr("r14", r14);
// lif("3 --------------------------------------------");
// dr();
var r14_mem = mrdr("r14");
lif("Memory at r14 " + r14_mem);
mwrr("r14", "0x696969");
lif("Memory at r14 " + mrdr("r14"));
mwrr("r14", r14_mem);
lif("Memory at r14 " + mrdr("r14"));
// var r14_mem = mrdr("r14");
// lif("Memory at r14 " + r14_mem);
// mwrr("r14", "0x696969");
// lif("Memory at r14 " + mrdr("r14"));
// mwrr("r14", r14_mem);
// lif("Memory at r14 " + mrdr("r14"));
// cont();

36
.debugusrc1.js.txt
View File

@@ -6,27 +6,27 @@ ler("Test error message");
var offset = "@DUPA_ADDR"; // dupa(), objdump -d ./test
// Testing...
pf();
ppid();
pplo();
// pf();
// ppid();
// pplo();
baddr(offset);
lsbrk();
lif("1 --------------------------------------------");
dr();
var r14 = gr("r14");
sr("r14", "0x0");
lif("2 --------------------------------------------");
dr();
sr("r14", r14);
lif("3 --------------------------------------------");
dr();
// lif("1 --------------------------------------------");
// dr();
// var r14 = gr("r14");
// sr("r14", "0x0");
// lif("2 --------------------------------------------");
// dr();
// sr("r14", r14);
// lif("3 --------------------------------------------");
// dr();
var r14_mem = mrdr("r14");
lif("Memory at r14 " + r14_mem);
mwrr("r14", "0x696969");
lif("Memory at r14 " + mrdr("r14"));
mwrr("r14", r14_mem);
lif("Memory at r14 " + mrdr("r14"));
// var r14_mem = mrdr("r14");
// lif("Memory at r14 " + r14_mem);
// mwrr("r14", "0x696969");
// lif("Memory at r14 " + mrdr("r14"));
// mwrr("r14", r14_mem);
// lif("Memory at r14 " + mrdr("r14"));
// cont();

4
da.h
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@@ -7,11 +7,11 @@
do { \
if ((da)->count == 0) { \
(da)->capacity = 1; \
(da)->items = malloc(sizeof(item)*sizeof((da)->capacity)); \
(da)->items = (typeof((da)->items))malloc(sizeof(item)*sizeof((da)->capacity)); \
} else { \
if ((da)->count == (da)->capacity) { \
(da)->capacity *= 2; \
(da)->items = realloc((da)->items, (da)->capacity * sizeof((item))); \
(da)->items = (typeof((da)->items))realloc((da)->items, (da)->capacity * sizeof((item))); \
} \
} \
(da)->items[(da)->count++] = (item); \

51
debugus.c
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@@ -145,6 +145,14 @@ void brk_disable(Brk *brk)
brk->enabled = false;
}
void symbols_deinit(Symbols *s)
{
for (int i = 0; i < s->count; i++) {
free((char *)s->items[i].name);
}
da_deinit(s);
}
typedef struct {
const char *file;
pid_t pid;
@@ -152,6 +160,8 @@ typedef struct {
HashTable brks;
uintptr_t program_load_offset;
HashTable js_descs;
Symbols symbols;
FILE *binfile;
PLibelfinBinding plibelfin;
} Dbg;
@@ -165,7 +175,26 @@ siginfo_t dbg_get_siginfo(Dbg *dbg)
void dbg_handle_sigsegv(Dbg *dbg, siginfo_t info)
{
unused(dbg);
uint64_t dbg_get_rip(Dbg *dbg);
LOG_ERR("Caught a segfault %d. SKILL ISSUE BRO\n", info.si_code);
uintptr_t rip = (uintptr_t)dbg_get_rip(dbg);
uintptr_t nearest = rip - dbg->symbols.items[0].addr;
for (int i = 0; i < dbg->symbols.count; i++) {
if (rip - dbg->symbols.items[i].addr < nearest) {
nearest = rip - dbg->symbols.items[i].addr;
}
}
uintptr_t addr = rip - nearest;
for (int i = 0; i < dbg->symbols.count; i++) {
if (dbg->symbols.items[i].addr == addr) {
AddrInfo *ai = libelfin_wrap_info_from_rip(dbg->plibelfin, (uint64_t)(addr - dbg->program_load_offset));
if (ai != NULL) {
LOG_INF("%s:%zu in function %s()\n", ai->file, (size_t)ai->line, dbg->symbols.items[i].name);
libelfin_wrap_free_info(ai);
}
break;
}
}
}
void dbg_handle_sigtrap(Dbg *dbg, siginfo_t info)
@@ -538,17 +567,29 @@ void dbg_load_script(Dbg *dbg, const char *script_path)
fclose(script);
}
void dbg_libelfin_wrap_init(Dbg *dbg)
void dbg_init_bin(Dbg *dbg)
{
FILE *bin = fopen(dbg->file, "rb");
if (bin == NULL) {
LOG_ERR("could not open file %s: %s\n", dbg->file, strerror(errno));
return;
}
dbg->binfile = bin;
}
dbg->plibelfin = libelfin_wrap_get_binding(fileno(bin));
void dbg_libelfin_wrap_init(Dbg *dbg)
{
dbg->plibelfin = libelfin_wrap_get_binding(fileno(dbg->binfile), dbg->program_load_offset);
}
fclose(bin);
void dbg_load_symbols(Dbg *dbg)
{
libelfin_wrap_get_syms(dbg->plibelfin, &dbg->symbols);
for (int i = 0; i < dbg->symbols.count; i++) {
Symbol *s = &dbg->symbols.items[i];
LOG_INF("Found symbol %s 0x%"PRIxPTR"\n", s->name, s->addr);
}
}
void dbg_init(Dbg *dbg, const char *file, pid_t pid)
@@ -559,7 +600,9 @@ void dbg_init(Dbg *dbg, const char *file, pid_t pid)
hashtable_init(&dbg->js_descs, MAX_JS_FUNCS);
dbg_init_js(dbg);
dbg_init_load_offset(dbg);
dbg_init_bin(dbg);
dbg_libelfin_wrap_init(dbg);
dbg_load_symbols(dbg);
hashtable_init(&dbg->brks, MAX_BRKS);
dbg_load_script(dbg, INIT_SCRIPT);
}
@@ -569,7 +612,9 @@ void dbg_deinit(Dbg *dbg)
js_freestate(dbg->js);
hashtable_deinit(&dbg->brks);
hashtable_deinit(&dbg->js_descs);
symbols_deinit(&dbg->symbols);
libelfin_wrap_free_binding(dbg->plibelfin);
fclose(dbg->binfile);
}
void dbg_loop(Dbg *dbg)

30
libelfin_wrap.cpp
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@@ -7,19 +7,41 @@
class LibelfinBinding
{
public:
LibelfinBinding(int fd)
LibelfinBinding(int fd, uintptr_t _loadoffset)
: elf(elf::create_mmap_loader(fd)),
dwarf(dwarf::elf::create_loader(this->elf))
dwarf(dwarf::elf::create_loader(this->elf)),
loadoffset(_loadoffset)
{
}
elf::elf elf;
dwarf::dwarf dwarf;
uintptr_t loadoffset;
};
DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd)
DEBUGUS_EXTERNC void libelfin_wrap_get_syms(PLibelfinBinding *pbind, Symbols *syms)
{
return (PLibelfinBinding)new LibelfinBinding(fd);
LibelfinBinding *bind = (LibelfinBinding *)pbind;
for (auto &section : bind->elf.sections()) {
if (section.get_hdr().type == elf::sht::symtab) {
for (auto sym : section.as_symtab()) {
auto &d = sym.get_data();
if (d.type() == elf::stt::func) {
Symbol s = {
.name = (const char *)malloc(strlen(sym.get_name().c_str())+1),
.addr = bind->loadoffset + (uintptr_t)d.value,
};
strcpy((char*)s.name, sym.get_name().c_str());
da_append(syms, s);
}
}
}
}
}
DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd, uintptr_t loadoffset)
{
return (PLibelfinBinding)new LibelfinBinding(fd, loadoffset);
}
DEBUGUS_EXTERNC void libelfin_wrap_free_binding(PLibelfinBinding pbind)

15
libelfin_wrap.h
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@@ -12,17 +12,30 @@
#include <stdlib.h>
#include <string.h>
#include "da.h"
typedef struct {
ssize_t line;
const char *file;
uint64_t addr;
} AddrInfo;
typedef struct {
const char *name;
uintptr_t addr;
} Symbol;
typedef struct {
Symbol *items;
size_t count, capacity;
} Symbols;
typedef void * PLibelfinBinding;
DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd);
DEBUGUS_EXTERNC PLibelfinBinding libelfin_wrap_get_binding(int fd, uintptr_t loadoffset);
DEBUGUS_EXTERNC void libelfin_wrap_free_binding(PLibelfinBinding pbind);
DEBUGUS_EXTERNC AddrInfo *libelfin_wrap_info_from_rip(PLibelfinBinding pbind, uint64_t rip);
DEBUGUS_EXTERNC void libelfin_wrap_free_info(AddrInfo *ai);
DEBUGUS_EXTERNC void libelfin_wrap_get_syms(PLibelfinBinding *pbind, Symbols *syms);
#endif // LIBELFIN_WRAP_H_

5
test.c
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@@ -1,5 +1,6 @@
#include <stdio.h>
#include <inttypes.h>
#include <stdlib.h>
void dupa(void) {
printf("KSKSKKSKSKSK\n");
@@ -15,6 +16,10 @@ int main(void)
dupa();
}
}
int *a = NULL;
*a = 6969;
return 0;
}