Closed Bug 738279 Opened 9 years ago Closed 9 years ago

crash in firebug-debugger after stepping over an bad object reference


(Core :: JavaScript Engine, defect)

11 Branch
Not set





(Reporter: atiware, Assigned: bhackett1024)



(Keywords: crash, reproducible)

Crash Data


(2 files, 1 obsolete file)

Attached file testcase-1
User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.6; rv:11.0) Gecko/20100101 Firefox/11.0
Build ID: 20120312181643

Steps to reproduce:

Debugged the attached testcase-1.

1. open Firebug, enable the script tab and load the attached testcase-1
2. debugger stops at breakpoint (A), (reload the site if the debugger don't stops)
3. click step over
4. now the cursor is at line (B), click step over again
5. now, hover the sourcecode in the firebug window at the bottom
6. crash

Firefox 11.0 + Firebug 1.9.1
Firefox nightly 14.0a1 (2012-03-22) + Firebug 10.0.a5

Crash ID: bp-1de8762a-de1f-4850-976d-afc0e2120322

Actual results:


Expected results:

don't crash
Attachment #608345 - Attachment mime type: text/plain → text/html
Severity: normal → critical
Crash Signature: [@ CrashIfInvalidSlot ]
Keywords: crash
Assignee: nobody → general
Blocks: 723445
Component: Untriaged → JavaScript Engine
Ever confirmed: true
Keywords: reproducible
Product: Firefox → Core
QA Contact: untriaged → general
Luke, this is crashing on CrashIfInvalidSlot called from

any idea offhand what that means?
Ooh yeah, this may be STR for bug 723445!  I'll investigate.
Wow, this is a most excellent test case; thanks!  I can reproduce locally, I'll look into it hopefully tomorrow.
Attached patch fix forced return (obsolete) — Splinter Review
Ah, I see the bug.  The problem is that forced_return (jumped to by the debugger) is setting the stack depth to 0, but leaving pc pointing to the JSOP_CALL which the debugger interrupted.  Thus, when the ScriptDebugEpilogue runs, js_ReconstructStackDepth(pc) is not equal to the actual stack depth and we go touching invalid memory (the next frame).

Thank you again Attila for taking the time to create a reproducible test-case.  It was certainly invaluable!  We've been trying to track down reports of this crash for a while and between this and bug 723445, I bet we have it fixed.
Attachment #612785 - Flags: review?(bhackett1024)
I forgot, I'll make a shell test-case tomorrow.
This patch adds a shell testcase.  In finding a testcase, I can see why this was relatively hard to hit: you have to trap on a 'call' instruction, force an early return, then, in the leave-frame hook for that function, you need to runs some code that inspects the stack via StackIter.  Phew.
Attachment #612785 - Attachment is obsolete: true
Attachment #612785 - Flags: review?(bhackett1024)
Attachment #612912 - Flags: review?(bhackett1024)
Attachment #612912 - Flags: review?(bhackett1024) → review+
Assignee: general → bhackett1024
Closed: 9 years ago
Resolution: --- → FIXED
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