[Gnuplot-info] glibc detected double free

[Olaf T. <ola...@un...>]

Hi,

with gnuplot-4.4.0 and -4.4.3, and with the cvs version of 2011-03-31,
glibc detects a double free. This happens regularly with the same
types of commands (i.e. plotting certain data in a certain way from
Octave), but not reproducibly with an exact procedure. Maybe there is
a racing condition involved (?) (but Gnuplot probably gets the correct
commands over the pipe, since Octave writes to the pipe blocking),
since it does not occur from an ssh login.

The glibc message for the cvs version (2011-03-31) is
attached. addr2line translates the gnuplot-part of the backtrace
to the following lines of code:

unset_tics
/home/olaf/gnuplot-cvs/gnuplot/src/unset.c:1179

unset_minitics
/home/olaf/gnuplot-cvs/gnuplot/src/unset.c:1156

do_line
/home/olaf/gnuplot-cvs/gnuplot/src/command.c:382

com_line
/home/olaf/gnuplot-cvs/gnuplot/src/command.c:332

main
/home/olaf/gnuplot-cvs/gnuplot/src/plot.c:652


which seems weird to me, since unset_minitics does not seem to call
unset_tics; but gnuplot had been compiled with -O2. Compiled without
optimization, the double free did not occur for me as yet under
conditions which most likely would have led to this double free if
compiled with -O2.

Maybe you can make something of this ...

Regards, Olaf