[user] segfault w/ error 4

[Ian Lance Taylor]

On Mon, Sep 10, 2012 at 10:06 PM, U.Mutlu <for-gmane@mutluit.com> wrote:

> recently a server daemon program suddenly started repeatedly crashing.
> syslog says:
>  segfault at 7f6d003d5453 ip 00007f6d49c9dd6d sp 00007f6d469c1b60 error 4 in
> libstdc++.so.6.0.17[7f6d49bff000+e8000]
>
> What does "error 4" mean? Is this documented somewhere?
>
> Is this an application error or rather an error in libstdc++.so ?
>
> The error is not always repeatable, ie. happens occasionally, reason unknown
> yet.
>
> What's the easiest method to locate the bug in this server daemon pgm?

That message does not come from libstdc++.  You neglected to mention
anything about the system, but that looks like the log from an x86
Linux kernel when a program crashes.  For the Linux kernel, error 4
means that this is a user-mode access.

You can get this kind of thing if you pass a NULL pointer to a
libstdc++ routine that is not expecting one, so this may be a bug in
your program.  Or it may be a bug in libstdc++.

Ian