py/emitbc: Add check for bytecode jump offset overflow.

Signed-off-by: Damien George <damien@micropython.org>
This commit is contained in:
Damien George 2022-03-18 13:18:59 +11:00
parent 538c3c0a55
commit acd2c5c834
3 changed files with 20 additions and 0 deletions

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@ -64,6 +64,7 @@ struct _emit_t {
size_t bytecode_offset; size_t bytecode_offset;
size_t bytecode_size; size_t bytecode_size;
byte *code_base; // stores both byte code and code info byte *code_base; // stores both byte code and code info
bool overflow;
size_t n_info; size_t n_info;
size_t n_cell; size_t n_cell;
@ -260,6 +261,9 @@ STATIC void emit_write_bytecode_byte_label(emit_t *emit, int stack_adj, byte b1,
if (is_signed) { if (is_signed) {
bytecode_offset += 0x4000; bytecode_offset += 0x4000;
} }
if (emit->pass == MP_PASS_EMIT && !(0 <= bytecode_offset && bytecode_offset <= 0x7fff)) {
emit->overflow = true;
}
c[1] = 0x80 | (bytecode_offset & 0x7f); c[1] = 0x80 | (bytecode_offset & 0x7f);
c[2] = bytecode_offset >> 7; c[2] = bytecode_offset >> 7;
} }
@ -274,6 +278,7 @@ void mp_emit_bc_start_pass(emit_t *emit, pass_kind_t pass, scope_t *scope) {
emit->last_source_line = 1; emit->last_source_line = 1;
emit->bytecode_offset = 0; emit->bytecode_offset = 0;
emit->code_info_offset = 0; emit->code_info_offset = 0;
emit->overflow = false;
// Write local state size, exception stack size, scope flags and number of arguments // Write local state size, exception stack size, scope flags and number of arguments
{ {
@ -373,6 +378,10 @@ bool mp_emit_bc_end_pass(emit_t *emit) {
return false; return false;
} }
if (emit->overflow) {
mp_raise_msg(&mp_type_RuntimeError, MP_ERROR_TEXT("bytecode overflow"));
}
// Bytecode is finalised, assign it to the raw code object. // Bytecode is finalised, assign it to the raw code object.
mp_emit_glue_assign_bytecode(emit->scope->raw_code, emit->code_base, mp_emit_glue_assign_bytecode(emit->scope->raw_code, emit->code_base,
#if MICROPY_PERSISTENT_CODE_SAVE || MICROPY_DEBUG_PRINTERS #if MICROPY_PERSISTENT_CODE_SAVE || MICROPY_DEBUG_PRINTERS

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@ -24,3 +24,10 @@ x = [1 if x else 123]
print(x) print(x)
""" """
) )
# Test overflow of jump offset.
for n in (430, 431, 432, 433):
try:
exec("cond = 0\nif cond:\n" + body * n + "else:\n print('cond false')\n")
except RuntimeError:
print("RuntimeError")

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@ -1 +1,5 @@
[123] [123]
cond false
cond false
RuntimeError
RuntimeError