Re: flexfax: HylaFax bug in SNPPserver

[Matthias.Apitz@SOFTCON.de]

thoth@purplefrog.com wrote:
    
    
      I have hylafax-v4.0pl1 on a RedHat 4.1 Linux box.  I'm trying to
    sendpage from a remote machine.  The hfaxd SEGVs on me.  When using
    sendpage from a local machine, it works just fine.
    
      Using my netpipes utilities and the wonderful GDB attach feature, I
    managed to nail the segment of code that is misbehaving:
    
    Program received signal SIGSEGV, Segmentation fault.
    0x806be56 in SNPPServer::loginCmd (this=0x80be6b8, loginID=0x80ba8f0 "thoth", 
        pass=0x0) at SNPPServer.c++:993
    993                 if (pass[0] == '\0' || !streq(crypt(pass, passwd), passwd)) 
    
      As you can see from the GDB stack dump, pass == 0, so dereferencing it
    will cause most OSs to SEGV (excepting the really wacky ones who map it
    to a NUL character).  Add a check to ensure that pass is non-0 .
    
      This bug will not be exercised if the user is authorized to use the
    service without a password.  Since I hadn't configured my etc/hosts
    properly, I suffered this bug.

Thanks for the bugfix; I think the simplest way is changing
in SNPPServer.h:

	void loginCmd(const char* loginID, const char* pwd = NULL);
to
	void loginCmd(const char* loginID, const char* pwd = "");


BTW: Do you have some information why some systems map a NULL pointer
to a 0x00 and others don't?

	matthias