Re: local users can panic linux kernel (was: SuSE syslogdadvisory)

From: Alessandro Rubini (rubiniat_private)
Date: Fri Nov 26 1999 - 04:48:58 PST

  • Next message: Christopher Rhodes: "Re: WordPad/riched20.dll buffer overflow"

    > <Linux specific>
    > I could make that trouble happen while testing by overloading the kernel
    > logging facility with a dumb logger ipchains policy looking like [...]
    
    The behaviour you describe only applies to kernel-generated log messages.
    
    This is because kernel messages are put in a circular buffer for later
    retrivial by user space (when syslogd gets scheduled for execution).
    
    If the buffer overlaps, you loose one-buffer-worth of data. Use of a
    dynamic buffer for kernel messages would not be wise, as it might lead
    to an easy DoS attack.
    
    > (BTW, if anyone could tell me how to increase that buffer, I'm still
    > interested)
    
    It wouldn't really help, in my opinion: you'll loose data more rarely,
    but you'll loose much more data when that happens. Anyways,
    change LOG_BUF_LEN in kernel/printk.c.
    
    /alessandro
    



    This archive was generated by hypermail 2b30 : Fri Apr 13 2001 - 15:14:27 PDT