tor-browser

commit c528ae17f04fdcfa150e5c0ae819bbd15a8d6e3e
parent 6d0c417da901c3fc86201674589dd5399fa48876
Author: Jon Coppeard <jcoppeard@mozilla.com>
Date:   Mon,  3 Nov 2025 17:23:14 +0000

Bug 1995637 - Make sure debugger object gets traced when tracing breakpoints r=iain

Breakpoints currently trace |wrappedDebugger| but this doesn't keep |debugger|
alive if we have nuked the CCWs. The debugger has a linked list of breakpoints that
each breakpoint is part of so we need to make sure it lives at least as long as
that.

The patch traces the debugger's object even if our CCW to it has been nuked.

Differential Revision: https://phabricator.services.mozilla.com/D271062

Diffstat:
M
js/src/debugger/Debugger.cpp
 | 
3
+++
A
js/src/jit-test/tests/debug/bug-1995637.js
 | 
66
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

2 files changed, 69 insertions(+), 0 deletions(-)
diff --git a/js/src/debugger/Debugger.cpp b/js/src/debugger/Debugger.cpp
@@ -453,6 +453,9 @@ Breakpoint::Breakpoint(Debugger* debugger, HandleObject wrappedDebugger,
 
 void Breakpoint::trace(JSTracer* trc) {
   TraceEdge(trc, &wrappedDebugger, "breakpoint owner");
+  // Trace the debugger object too in case |wrappedDebugger| got nuked.
+  TraceCrossCompartmentEdge(trc, wrappedDebugger, &debugger->object,
+                            "breakpoint debugger object");
   TraceEdge(trc, &handler, "breakpoint handler");
 }
 
diff --git a/js/src/jit-test/tests/debug/bug-1995637.js b/js/src/jit-test/tests/debug/bug-1995637.js
@@ -0,0 +1,66 @@
+// |jit-test| error: TypeError
+gczeal(9,16);
+function F1() {
+    if (!new.target) { throw 'must be called with new'; }
+    this.b = null;
+}
+new F1();
+new F1();
+function f5() {}
+new BigUint64Array(3474);
+function f14() {}
+function f25(a26, a27) {
+    for (let i30 = 0, i31 = true; i31; i31--) {
+        function f37() {
+            function F38() {}
+            for (let i44 = 0, i45 = SharedArrayBuffer; i45;
+                (() => {
+                    i45--;
+                    Int8Array.principal = BigUint64Array;
+                    function F50() {}
+                    Int8Array.sameZoneAs = /wp(?:a?)+/imu;
+                    const v54 = this.newGlobal(Int8Array);
+                    const t7 = ({ __proto__: v54 }).Debugger;
+                    const v57 = t7(F50);
+                    const v59 = v57.getNewestFrame(i30, i45, i45, f25, v57).older;
+                    v59.script.setBreakpoint(16, v59);
+                })()) {}
+            for (let [i134, i135] = (() => {
+                    for (let i84 = 0, i85 = 10; i85;
+                        (() => {
+                            i85--;
+                            for (let [i102, i103] = (() => {
+                                    for (let [i95, i96] = (() => {
+                                            new Uint8Array();
+                                            return [0, 10];
+                                        })(); i96; i96--) {
+                                    }
+                                    return [0, SharedArrayBuffer];
+                                })();
+                                i103; i103--) {}
+                            for (let i113 = -4, i114 = 10; i114; i114--) {}
+                            for (let i122 = 4, i123 = 10; i123--, i123; i123--) {
+                                i123++;
+                            }
+                        })()) {}
+                    return [0, SharedArrayBuffer];
+                })();
+                i135; i135--) {            }
+            for (let i143 = 0, i144 = 10; i144; i144--) {}
+        }
+        f37.apply();
+    }
+    for (let i153 = 0, i154 = 10; i154; i154--) {}
+    function F160(a162, a163) {
+        if (!new.target) { throw 'must be called with new'; }
+        this.c = a27;
+        this.h = a162;
+    }
+    new F160(234, a27);
+    const v167 = this.nukeAllCCWs();
+    for (let i170 = 0, i171 = 10; i171; i171--) {}
+    try {
+        f25();
+    } catch(e178) {}
+}
+f25(f25, f25);