79581 - XPConnect error message misleading when secman denies wrapper building

Status: VERIFIED DUPLICATE of bug 70162

(Core :: Security: CAPS, defect)

Description

[Simon Fraser [no longer active]]

Bug 79544 describes a problem where a security check failure caused a JS error 
like:

************************************************************
* Call to xpconnect wrapped JSObject produced this error:  *
[Exception... "Permission denied to create wrapper for object
[nsIDocumentStateListener::NotifyDocumentCreated]"  nsresult: "0x8057001e
(NS_ERROR_XPC_JS_THREW_STRING)"  location: "<unknown>"  data: no]
************************************************************

This error implies that the security check failed when trying to create a wrapper 
for nsIDocumentStateListener::NotifyDocumentCreated. The real bug was that 
IsDOMClass() was failing for nsDOMDocumentType, which was used as a local 
variable in one of the JS functions that NotifyDocumentCreated() called.

Comment 1

[John Bandhauer]

OK. I've been debugging. The problem is that we don't catch this exception at 
the place it is generated. When we catch it later we assume it has to do with 
the current call. so, it gets tagged with info about the current call that is 
not correct. It looks like the fix is going to be to not let the exception spil 
through the cracks in the first place.

Comment 2

[John Bandhauer]

Well, I retract my statement about the exception getting left over for later.

For xpconnect's part it is misleading that xpconnect just concat's the 
[interfacename:methodname] onto the back of the thrown string. I propose the 
following change in the format string used in xpconnect:

Index: xpcconvert.cpp
===================================================================
RCS file: /cvsroot/mozilla/js/src/xpconnect/src/xpcconvert.cpp,v
retrieving revision 1.57
diff -r1.57 xpcconvert.cpp
978c978
<     static const char format[] = "%s [%s::%s]";
---
>     static const char format[] = "\'%s\' when calling method: [%s::%s]";


This will turn the message into:

************************************************************
* Call to xpconnect wrapped JSObject produced this error:  *
[Exception... "'Permission denied to create wrapper for object' 
when calling method: [nsIDocumentStateListener::NotifyDocumentCreated]" 
nsresult: "0x8057001e (NS_ERROR_XPC_JS_THREW_STRING)"  location: 
"<unknown>"  data: no]
************************************************************

The above quotes the part that caps set.

This is a no-brainer fix in xpconnect.

I say that the real bug is that caps does not give a more detailed error 
message. *It* sets the original JS exception that xpconnect later builds on. And 
at that point caps has nsIClassInfo (so can get the likely classname - if 
available) and it has iid info about the class we are trying to wrap (or get a 
property of or whatever).

So, I can checkin my little patch to make this a little less confusing. And the 
bug goes to caps to improve its part.

Comment 3

[Mitchell Stoltz (not reading bugmail)]

*** This bug has been marked as a duplicate of 70162 ***

Comment 4

[ckritzer (gone)]

Marking VERIFIED DUPLICATE.