PRBool IsChildOfDomWindow(nsIDOMWindow *parent, nsIDOMWindow *child) { if (parent == child) return PR_TRUE; nsCOMPtr<nsIDOMWindow> childsParent; child->GetParent(getter_AddRefs(childsParent)); if (!childsParent) // <--------- (A) return PR_FALSE; return IsChildOfDomWindow(parent, childsParent); } if I do not check to see if the childsParent == parent at (A), I crash on some pages. To reproduce this: 1. Goto http://www.mozilla.org/ 2. Click on Report A Bug on the left side of the document. This will you to http://www.mozilla.org/quality/help/bug-form.html. 3. Right click on the link that says "Create a Bugzilla Account". 4. Select "Open Link in new window". 5. In this new window, type in a bug number at the bottom of the screen and click "Find". Crash occurs. PR_AtomicIncrement(int * 0x038ecb00) line 285 + 4 bytes nsDocShell::AddRef(nsDocShell * const 0x038ecad0) line 122 + 52 bytes nsWebShell::AddRef(nsWebShell * const 0x038ecad0) line 488 + 12 bytes nsDocShell::QueryInterface(nsDocShell * const 0x038ecad0, const nsID & {...}, void * * 0x00033090) line 138 + 57 bytes nsWebShell::QueryInterface(nsWebShell * const 0x038ecad0, const nsID & {...}, void * * 0x000330c4) line 513 + 30 bytes nsQueryInterface::operator()(const nsID & {...}, void * * 0x000330c4) line 32 + 25 bytes nsCOMPtr<nsIDocShellTreeItem>::assign_from_helper(const nsCOMPtr_helper & {...}, const nsID & {...}) line 825 + 18 bytes nsCOMPtr<nsIDocShellTreeItem>::nsCOMPtr<nsIDocShellTreeItem>(const nsQueryInterface & {...}) line 538 GlobalWindowImpl::GetParent(GlobalWindowImpl * const 0x038e57b4, nsIDOMWindow * * 0x0003314c) line 516 IsChildOfDomWindow(nsIDOMWindow * 0x0307fb04, nsIDOMWindow * 0x038e57b4) line 226 + 36 bytes IsChildOfDomWindow(nsIDOMWindow * 0x0307fb04, nsIDOMWindow * 0x038e57b4) line 230 + 18 bytes ... (recursive call leads to stack overflow)

This is needed for beta2, given the crash; giving PDT approval.

I had a look at this today and it turns out that this is is an invalid bug, even if I was sure this was a bug. So the deal is that if a window doesn't have a parent, it returns itself, the reason for this is probably backwards compatibility since 4.x does the same thing. The reason for this bug IIRC is that I told dougt to file it since I thought that GetParent() would return null if there's no parent, but that's not the case, I don't knoe exacly why? I checked the code and it does the proper checking for this, ie there is no crash due to this at the moment. I'm marking this bug INVALID, but it's my bad that it got filed in the first place.

As per Johnny, marking it verified.