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GH-91079: Implement C stack limits using addresses, not counters. (GH-130007)

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* Implement C recursion protection with limit pointers

* Remove calls to PyOS_CheckStack

* Add stack protection to parser

* Make tests more robust to low stacks

* Improve error messages for stack overflow
This commit is contained in:
Mark Shannon 2025-02-19 11:44:57 +00:00 • committed by GitHub
parent c637bce20a
commit 2498c22fa0
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GPG key ID: B5690EEEBB952194
47 changed files with 1217 additions and 1463 deletions
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56
Python/ast_opt.c
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@ -10,24 +10,14 @@
typedef struct {
int optimize;
int ff_features;
int recursion_depth; /* current recursion depth */
int recursion_limit; /* recursion limit */
} _PyASTOptimizeState;
#define ENTER_RECURSIVE(ST) \
do { \
if (++(ST)->recursion_depth > (ST)->recursion_limit) { \
PyErr_SetString(PyExc_RecursionError, \
"maximum recursion depth exceeded during compilation"); \
return 0; \
} \
} while(0)
#define ENTER_RECURSIVE() \
if (Py_EnterRecursiveCall(" during compilation")) { \
return 0; \
}
#define LEAVE_RECURSIVE(ST) \
do { \
--(ST)->recursion_depth; \
} while(0)
#define LEAVE_RECURSIVE() Py_LeaveRecursiveCall();
static int
make_const(expr_ty node, PyObject *val, PyArena *arena)
@ -668,7 +658,7 @@ astfold_mod(mod_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
static int
astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
ENTER_RECURSIVE(state);
ENTER_RECURSIVE();
switch (node_->kind) {
case BoolOp_kind:
CALL_SEQ(astfold_expr, expr, node_->v.BoolOp.values);
@ -765,7 +755,7 @@ astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
case Name_kind:
if (node_->v.Name.ctx == Load &&
_PyUnicode_EqualToASCIIString(node_->v.Name.id, "__debug__")) {
LEAVE_RECURSIVE(state);
LEAVE_RECURSIVE();
return make_const(node_, PyBool_FromLong(!state->optimize), ctx_);
}
break;
@ -778,7 +768,7 @@ astfold_expr(expr_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
// No default case, so the compiler will emit a warning if new expression
// kinds are added without being handled here
}
LEAVE_RECURSIVE(state);;
LEAVE_RECURSIVE();
return 1;
}
@ -823,7 +813,7 @@ astfold_arg(arg_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
static int
astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
{
ENTER_RECURSIVE(state);
ENTER_RECURSIVE();
switch (node_->kind) {
case FunctionDef_kind:
CALL_SEQ(astfold_type_param, type_param, node_->v.FunctionDef.type_params);
@ -945,7 +935,7 @@ astfold_stmt(stmt_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
// No default case, so the compiler will emit a warning if new statement
// kinds are added without being handled here
}
LEAVE_RECURSIVE(state);
LEAVE_RECURSIVE();
return 1;
}
@ -977,7 +967,7 @@ astfold_pattern(pattern_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
// Currently, this is really only used to form complex/negative numeric
// constants in MatchValue and MatchMapping nodes
// We still recurse into all subexpressions and subpatterns anyway
ENTER_RECURSIVE(state);
ENTER_RECURSIVE();
switch (node_->kind) {
case MatchValue_kind:
CALL(astfold_expr, expr_ty, node_->v.MatchValue.value);
@ -1009,7 +999,7 @@ astfold_pattern(pattern_ty node_, PyArena *ctx_, _PyASTOptimizeState *state)
// No default case, so the compiler will emit a warning if new pattern
// kinds are added without being handled here
}
LEAVE_RECURSIVE(state);
LEAVE_RECURSIVE();
return 1;
}
@ -1047,34 +1037,12 @@ astfold_type_param(type_param_ty node_, PyArena *ctx_, _PyASTOptimizeState *stat
int
_PyAST_Optimize(mod_ty mod, PyArena *arena, int optimize, int ff_features)
{
PyThreadState *tstate;
int starting_recursion_depth;
_PyASTOptimizeState state;
state.optimize = optimize;
state.ff_features = ff_features;
/* Setup recursion depth check counters */
tstate = _PyThreadState_GET();
if (!tstate) {
return 0;
}
/* Be careful here to prevent overflow. */
int recursion_depth = Py_C_RECURSION_LIMIT - tstate->c_recursion_remaining;
starting_recursion_depth = recursion_depth;
state.recursion_depth = starting_recursion_depth;
state.recursion_limit = Py_C_RECURSION_LIMIT;
int ret = astfold_mod(mod, arena, &state);
assert(ret || PyErr_Occurred());
/* Check that the recursion depth counting balanced correctly */
if (ret && state.recursion_depth != starting_recursion_depth) {
PyErr_Format(PyExc_SystemError,
"AST optimizer recursion depth mismatch (before=%d, after=%d)",
starting_recursion_depth, state.recursion_depth);
return 0;
}
return ret;
}