395217 - uninitialized variable in nsHttpNTLMAuth::ChallengeReceived - intermittent sys-ntlm authentication failure

Status: RESOLVED INVALID

(Firefox :: Shell Integration, defect)

Description

[Laurenz Albe]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.0; de; rv:1.8.0.9) Gecko/20061206 Firefox/1.5.0.9
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.0; de; rv:1.8.0.9) Gecko/20061206 Firefox/1.5.0.9

I am experiencing intermittent NTLM authentication problems with Firefox 1.5.0.9 and 2.0.0.6.

We use squid as HTTP proxy with NTLM authentication.
network.automatic-ntlm-auth.allow-proxies is true, the proxy is in the domain wien.gv.at, and network.automatic-ntlm-auth.trusted-uris is set to ".magwien.gv.at, .wien.gv.at".

Normally things work like expected, and I can use the proxy.
Occasionally, however, I am prompted for user and password by Firefox and get the proxy's 407 page when I hit "cancel".
When I push the "reload" button, I get the page I requested without having to authenticate.

I ran a trace with NSPR_LOG_MODULES to nsHttp:5,nsSocketTransport:5.
I'll attach snippets of the log file to this bug.

Looking at the trace, I got the impression that the problem must be somewhere in nsHttpNTLMAuth::ChallengeReceived and examined the source code.

In line 229 of mozilla/netwerk/protocol/http/src/nsHttpNTLMAuth.cpp in seamonkey an automatic variable is declared, but not initialized:
        nsCOMPtr<nsISupports> module;

The log tells me that the *continuationState is nonzero, so the condition in line 246 becomes false and module is not assigned to in the next line.

In the query
        if (!module) {
in line 255 module may still be uninitialized, which (if I didn't misinterpret the trace) could lead to the observed problem.

Reproducible: Sometimes

Steps to Reproduce:
1. request a page from https://metalink.oracle.com (after having logged in)
2. repeat step 1. until the problem occurs
Actual Results:  
A popup asks me for user-ID and password. If I enter the correct user-ID and password, the page is loaded correctly. If I hit "cancel", I get the 407 page from the proxy server.

Expected Results:  
Get the correct page without having to authenticate. This is what happens normally.

Comment 1

[Laurenz Albe]

Attachment: Part of a trace with NSPR_LOG_MODULES=nsHttp:5,nsSocketTransport:5

There are two snippets from the log file: part of a successful attemt to get a page, and part of a failed attempt

Comment 2

[Laurenz Albe]

Maybe the uninitialized variable (which IS a problem) is not the immediate cause of the problem I observe:

I notice that in the error case the continuationState passed to ChallengeReceived is non-zero, although we are not in the middle of NTLM authentication.

Usually the pattern is like this:
1) A request is sent.
2) A response comes in with "Proxy-Authenticate: NTLM", continuationState is zero (visible as "cs=0" in the log entry of ChallengeReceived).
3) The request is resent with NTLMSSP NEGOTIATE.
4) A response comes in with "Proxy-Authenticate: NTLM TlRMTVN..." (NTLMSSP CHALLENGE), continuationState is nonzero
5) The request is resent with NTLMSSP AUTH.
6) Response "200 Connection established"

The problem cases differ in Step 2. A response with "Proxy-Authenticate: NTLM" comes, but continuationState is not zero.

What could cause this?

Comment 3

[Laurenz Albe]

I just read http://www.mozilla.org/projects/xpcom/nsCOMPtr.html and realize that the variable IS initialized.

I will close the bug because it is a mess.

I'll have to dig deeper - when I find the cause of the problem I experience, I will open a new bug.