ipv6 activity causing system hang in kernel 2.4.4

From: Tim Haynes (kernel@stirfried.vegetable.org.uk)
Date: Sat May 05 2001 - 19:17:47 EDT

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        [I can't see evidence of this being reported before; apols if I'm
         wrong. Please also Cc: me as I only read l-k intermittently but would
         like to help out more.]

    Hi,

    I've been making very tentative forays into IPv6. However, in my simple
    experiments thus far I appear to have located a bug:

    1/ configure 2 machines with site-local IP#s - I'm using
            ifconfig eth0 inet6 add fec0:1234:5:6::n
    2/ flood-ping from one to the other
    3/ after about 15s, watch one box hang, needing magic-sysreq or hard reset

    This is only with kernel 2.4.4; 2.4.2, 2.4.3 and NetBSD boxes are not
    affected. It is independent of platform; I've reproduced it at will on a
    lowly p75, an athlon, a p3-800 and on a powerbook/PPC.

    All kernels are compiled to have ipv6 modular, netfilter modular...
    everything with which I'm playing, modular.

    Compiler versions:
    | zsh, 12:06AM % gcc -v
    | Reading specs from /usr/lib/gcc-lib/powerpc-linux/2.95.4/specs
    | gcc version 2.95.4 20010319 (Debian prerelease)
    | zsh, 12:06AM % gcc -v
    | Reading specs from /usr/lib/gcc-lib/i386-linux/2.95.4/specs
    | gcc version 2.95.4 20010319 (Debian prerelease)
    (I'm tracking Debian/Unstable here.)

    I have tcpdump logs (<http://spodzone.org.uk/~tim/ipv6/> - they're 570K
    apiece); the `victim' machine receives nothing but ping-requests and sends
    nothing but ping-replies until the file is truncated; the surviving box
    sends nothing but requests and receives nothing but replies until it
    becomes requests-only. (IOW there is no evidence of ARP, fragmentation
    traffic, only the pings.)

    The Changelog lists an `IPv6 packet re-assembly fix' in -pre2; my
    suspicions lie in this area or with my compiler.

    If there's anything else I can provide by way of diagnostics, please let me
    know.

    Cheers,

    ~Tim 

    -- 
<http://spodzone.org.uk/>
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    This archive was generated by hypermail 2b29 : Sat May 05 2001 - 19:21:34 EDT