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gh-140815: Fix faulthandler for invalid/freed frame (#140921)

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faulthandler now detects if a frame or a code object is invalid or
freed.

Add helper functions:

* _PyCode_SafeAddr2Line()
* _PyFrame_SafeGetCode()
* _PyFrame_SafeGetLasti()

_PyMem_IsPtrFreed() now detects pointers in [-0xff, 0xff] range
as freed.
This commit is contained in:
Victor Stinner 2025-11-04 11:48:28 +01:00 • committed by GitHub
parent 08115d241a
commit a84181c31b
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GPG key ID: B5690EEEBB952194
6 changed files with 128 additions and 33 deletions
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62
Python/traceback.c
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@ -1028,14 +1028,24 @@ _Py_DumpWideString(int fd, wchar_t *str)
/* Write a frame into the file fd: "File "xxx", line xxx in xxx".
This function is signal safe. */
This function is signal safe.
static void
Return 0 on success. Return -1 if the frame is invalid. */
static int
dump_frame(int fd, _PyInterpreterFrame *frame)
{
assert(frame->owner < FRAME_OWNED_BY_INTERPRETER);
if (frame->owner == FRAME_OWNED_BY_INTERPRETER) {
/* Ignore trampoline frame */
return 0;
}
PyCodeObject *code =_PyFrame_GetCode(frame);
PyCodeObject *code = _PyFrame_SafeGetCode(frame);
if (code == NULL) {
return -1;
}
int res = 0;
PUTS(fd, " File ");
if (code->co_filename != NULL
&& PyUnicode_Check(code->co_filename))
@ -1043,29 +1053,36 @@ dump_frame(int fd, _PyInterpreterFrame *frame)
PUTS(fd, "\"");
_Py_DumpASCII(fd, code->co_filename);
PUTS(fd, "\"");
} else {
PUTS(fd, "???");
}
int lasti = PyUnstable_InterpreterFrame_GetLasti(frame);
int lineno = _PyCode_Addr2LineNoTstate(code, lasti);
else {
PUTS(fd, "???");
res = -1;
}
PUTS(fd, ", line ");
int lasti = _PyFrame_SafeGetLasti(frame);
int lineno = -1;
if (lasti >= 0) {
lineno = _PyCode_SafeAddr2Line(code, lasti);
}
if (lineno >= 0) {
_Py_DumpDecimal(fd, (size_t)lineno);
}
else {
PUTS(fd, "???");
res = -1;
}
PUTS(fd, " in ");
if (code->co_name != NULL
&& PyUnicode_Check(code->co_name)) {
PUTS(fd, " in ");
if (code->co_name != NULL && PyUnicode_Check(code->co_name)) {
_Py_DumpASCII(fd, code->co_name);
}
else {
PUTS(fd, "???");
res = -1;
}
PUTS(fd, "\n");
return res;
}
static int
@ -1108,17 +1125,6 @@ dump_traceback(int fd, PyThreadState *tstate, int write_header)
unsigned int depth = 0;
while (1) {
if (frame->owner == FRAME_OWNED_BY_INTERPRETER) {
/* Trampoline frame */
frame = frame->previous;
if (frame == NULL) {
break;
}
/* Can't have more than one shim frame in a row */
assert(frame->owner != FRAME_OWNED_BY_INTERPRETER);
}
if (MAX_FRAME_DEPTH <= depth) {
if (MAX_FRAME_DEPTH < depth) {
PUTS(fd, "plus ");
@ -1128,7 +1134,15 @@ dump_traceback(int fd, PyThreadState *tstate, int write_header)
break;
}
dump_frame(fd, frame);
if (_PyMem_IsPtrFreed(frame)) {
PUTS(fd, " <freed frame>\n");
break;
}
if (dump_frame(fd, frame) < 0) {
PUTS(fd, " <invalid frame>\n");
break;
}
frame = frame->previous;
if (frame == NULL) {
break;