Re: Nmap stops with error: "buffer 0verfl0w of familygenerations" on large scans

[David Fifield <david () bamsoftware com>]

On Fri, Nov 16, 2012 at 10:26:00AM +0100, Jan Kaestle wrote:
> Hi,
>
> nmap stops on large scans with the error "buffer 0verfl0w of
> familygenerations QUITTING!". Nmap just prints out this message and
> stops. I got this error several times after scanning a few thousands
> up to at most 40.000 hosts with OS and version detection enabled.
>
> This is the command I used:
>
> nmap -v -T4 -sS -Pn --top-ports 100 -n -sV --host-timeout 10m -O -oA
> nmap_tcp_top100_1 -iL active_ips_all_1.txt
>
> The error is printed in line 1541 in output.cc:
> if (flen + 2 + strlen(OSR->OSC[classno]->OS_Generation) >=
>     sizeof(familygenerations[familyno]))
>   fatal("buffer 0verfl0w of familygenerations");
>
> The error both occured on Debian 6.0.6 and Ubuntu 12.04
>
> I am using Nmap 6.01.
>
> For me I could fix this bug by doubling the array that is allocated in
> line 1489 of output.cc
>
> char familygenerations[MAX_OS_CLASSMEMBERS][96];

Thanks for this. I have committed the change increasing the buffer
length.

It might help if you can show us what strings are being concatenated to
make the result too long. If you can, please try this debugging patch
and send us the output.

David Fifield

Attachment: familygenerations-log.patch
Description:

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