Re: [Samba] [3.2.0] Off by one error - Samba

This is a discussion on Re: [Samba] [3.2.0] Off by one error - Samba ; ----- Original Message ----- From: "Jeremy Allison" Newsgroups: linux.samba Sent: Wednesday, July 02, 2008 2:20 PM Subject: Re: [Samba] [3.2.0] Off by one error > >> I'd need some pointers, I'm not all that familiar with gdb, and there is ...

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Thread: Re: [Samba] [3.2.0] Off by one error

  1. Re: [Samba] [3.2.0] Off by one error

    ----- Original Message -----
    From: "Jeremy Allison"
    Newsgroups: linux.samba
    Sent: Wednesday, July 02, 2008 2:20 PM
    Subject: Re: [Samba] [3.2.0] Off by one error


    >
    >> I'd need some pointers, I'm not all that familiar with gdb, and there is
    >> no way to stop on the error. NMDB still runs after displaying this; so,
    >> I don't think a back-trace will help find it when I kill the process.

    >
    > What you can do is attach to the running process with :
    >
    > gdb /usr/local/samba/sbin/nmbd
    > b lib/util_str.c:safe_strcpy_fn:709
    > attach
    > continue
    >
    > Then when the breakpoint triggers you can type :
    >
    > bt
    >
    > to get the backtrace, and also go up the stack
    > and type out the local variables.
    >
    > If it happens every time you start nmbd then
    > that's easier, just type :
    >
    > gdb --args /usr/local/samba/sbin/nmbd -i
    > b lib/util_str.c:safe_strcpy_fn:709
    > run
    >
    > Thanks !
    >
    > Jeremy


    I'll have to get back to you later on the backtrace gdb is broken on my
    machine.
    It is 100% reproducable by including an interfaces line with the IP and mask
    as the parameter. And only happens on startup when nmbd is loading the
    configuration. If I change the interfaces line to read just the single IP
    without the mask all is fine.
    I'll check to see if this was a change to how the interface line is
    specified or a problem that has always been there. And wasn't caught until
    safe-copy was used.

    interfaces 192.168.100.20/24
    breaks the nmdb with an error; but doesn't stop nmdb.
    interfaces 192.168.100.20
    works and no error is reported.

    James Kosin

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  2. Re: [Samba] [3.2.0] Off by one error

    On Wed, Jul 02, 2008 at 06:46:50PM -0400, James Kosin wrote:

    > I'll have to get back to you later on the backtrace gdb is broken on my
    > machine.
    > It is 100% reproducable by including an interfaces line with the IP and
    > mask as the parameter. And only happens on startup when nmbd is loading
    > the configuration. If I change the interfaces line to read just the single
    > IP without the mask all is fine.
    > I'll check to see if this was a change to how the interface line is
    > specified or a problem that has always been there. And wasn't caught until
    > safe-copy was used.
    >
    > interfaces 192.168.100.20/24
    > breaks the nmdb with an error; but doesn't stop nmdb.
    > interfaces 192.168.100.20
    > works and no error is reported.


    Ok, I've found it. It's a warning, not an error.
    We've correctly set up the interface here but
    we're just trying to set the interface name.

    It happens here lib/interface.c:

    472 safe_strcpy(ifs.name, token, sizeof(ifs.name)-1);

    Where token is set to "192.168.100.20/24" which is greater
    than ifs.name. We've already parsed out the values for
    ss, ss_mask and ss_bcast we're just trying to give the
    pseudo interface a name.

    I'll replace this with strlcpy and it should be fine.

    Thanks for the report though !

    Jeremy.
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