The Jargon File (version 4.4.7, 29 Dec 2003):

buffer overflow
 n.

    What happens when you try to stuff more data into a buffer (holding area)
    than it can handle. This problem is commonly exploited by crackers to get
    arbitrary commands executed by a program running with root permissions.
    This may be due to a mismatch in the processing rates of the producing and
    consuming processes (see overrun and firehose syndrome), or because the
    buffer is simply too small to hold all the data that must accumulate before
    a piece of it can be processed. For example, in a text-processing tool that
    crunches a line at a time, a short line buffer can result in lossage as
    input from a long line overflows the buffer and trashes data beyond it.
    Good defensive programming would check for overflow on each character and
    stop accepting data when the buffer is full up. The term is used of and by
    humans in a metaphorical sense. ?What time did I agree to meet you? My
    buffer must have overflowed.? Or ?If I answer that phone my buffer is going
    to overflow.? See also spam, overrun screw.


The Free On-line Dictionary of Computing (30 December 2018):

buffer overflow
buffer overrun

    What happens when you try to store more data in
   a buffer than it can handle.  This may be due to a mismatch
   in the processing rates of the producing and consuming
   processes (see overrun and firehose syndrome), or because
   the buffer is simply too small to hold all the data that must
   accumulate before a piece of it can be processed.  For
   example, in a text-processing tool that crunches a line at a
   time, a short line buffer can result in lossage as input
   from a long line overflows the buffer and overwrites data
   beyond it.  Good defensive programming would check for
   overflow on each character and stop accepting data when the
   buffer is full.

   See also spam, overrun screw.

   [Jargon File]

   (1996-05-13)