segfault when using freopen() after an ld preloaded wrapped fopen()

[Geert Bevin]

Environment:
Gentoo Linux 1.0
Redhat Linux 7.2

Description:

When working on a sandbox solution using the ld preload mechanism, I
came accross a weird behaviour. When creating a wrapper for fopen() and
freopen() (wrapped or non-wrapped) is later used, libc segfaults on all
the subsequent calls that use the newly returned FILE stream.

How-To-Repeat
Untar the above archive, cd into it and type make.
Then run ./sandbox_freopenbug and you get:
unlink
... done
fopen
... done
fputc
... done
fseek
... done
freopen
... done
fgetc 7
... done
fseek
... done
fclose
... done

Then add /path/to/libsandbox_freopenbug.so to /etc/ld.so.preload

Then run ./sandbox_freopenbug again and you get :
unlink
... done
fopen
... done
fputc
... done
fseek
... done
freopen
... done
Segmentation fault

-- 
Geert Bevin             Uwyn
"Use what you need"     Lambermontlaan 148
http://www.uwyn.com     1030 Brussels
address@hidden         Tel & Fax +32 2 245 41 06

glibc_bug.tar
Description: Unix tar archive