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@murx-

murx-/gdb_script.py

Created Dec 1, 2020
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Use GDB to trace two variables and check if the offset/pointer value has grown beyond the end value
# Trace two variables and check if the offset/pointer value has grown beyond the end
# We assume/know that rl_point > rl_end is true as we use reverse debugging with rr
# We want to find the point were everything was okay.
# enter "interactive" python shell with 'pi' and exit after pasting with 'ctrl+d'
POINT_VAR_NAME = 'rl_point'
END_VAR_NAME = 'rl_end'
class bcolors:
FAIL = '\033[91m'
ENDC = '\033[0m'
BOLD = '\033[1m'
UNDERLINE = '\033[4m'
class CompareBreakpoint(gdb.Breakpoint):
def stop(self):
point_value = gdb.lookup_symbol(POINT_VAR_NAME)[0].value()
end_value = gdb.lookup_symbol(END_VAR_NAME)[0].value()
#if a difference of e.g. 1 is accetable
#if (end_value - point_value) < -1:
if point_value <= end_value:
print(f'{bcolors.FAIL} {bcolors.BOLD} {bcolors.UNDERLINE}')
print(f'[!] {END_VAR_NAME}: {end_value} \t {POINT_VAR_NAME}: {point_value}')
print(f'{bcolors.ENDC}', end='')
return True
return False
CompareBreakpoint(END_VAR_NAME, gdb.BP_WATCHPOINT, gdb.WP_WRITE)
CompareBreakpoint(POINT_VAR_NAME, gdb.BP_WATCHPOINT, gdb.WP_WRITE)
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