On Sun, 27 Nov 2011 19:29:44 -0500, Daniel Kahn Gillmor <[email protected]> wrote: > trying to do a minimal operation within the chroot for debugging, i get: > > 0 consoleuser@stylus:~/fakechroot$ fakechroot /usr/sbin/chroot $(pwd)/stable > /bin/true > Segmentation fault > 139 consoleuser@stylus:~/fakechroot$
This appears to be related to an interaction between ld-linux.so.2 from
sid's libc6 (2.13-21) and libc.so.6 from squeeze's libc6 (2.11.2-10).
Here we see that libc works fine against the old ld-linux, but segfaults
with the new ld-linux:
0 root@stylus:/tmp# find x \! -type d -ls
862137 16 -rwxr-xr-x 1 root root 16060 Nov 27 20:32 x/bin/true
862136 1296 -rwxr-xr-x 1 root root 1319176 Nov 27 20:31
x/lib/libc-2.11.2.so
862142 1292 -rwxr-xr-x 1 root root 1314952 Nov 27 21:40
x/lib/libc-2.13.so
862140 116 -rwxr-xr-x 1 root root 113964 Nov 27 21:10
x/lib/ld-2.11.2.so
862141 120 -rwxr-xr-x 1 root root 117960 Nov 27 21:10
x/lib/ld-2.13.so
862138 0 lrwxrwxrwx 1 root root 14 Nov 27 20:32
x/lib/libc.so.6 -> libc-2.11.2.so
862139 0 lrwxrwxrwx 1 root root 12 Nov 27 21:14
x/lib/ld-linux.so.2 -> ld-2.11.2.so
0 root@stylus:/tmp# chroot x /bin/true
0 root@stylus:/tmp# ln -sf ld-2.13.so x/lib/ld-linux.so.2
0 root@stylus:/tmp# chroot x /bin/true
Segmentation fault
139 root@stylus:/tmp#
Since fakechroot can't intercept the loading of ld-linux.so (the
LD_PRELOAD hack is actually implemented by ld-linux.so itself), the
resulting process of a fakechroot invocation from sid to squeeze is
using sid's ld-linux to load squeeze's libc6, which causes the
segmentation fault seen above.
Should we be able to expect to run squeeze's libc against sid's
ld-linux.so? I don't know.
I do note that we can use squeeze's ld-linux against sid's libc, though:
0 root@stylus:/tmp# ls -l x/lib
total 2824
-rwxr-xr-x 1 root root 113964 Nov 27 21:10 ld-2.11.2.so
-rwxr-xr-x 1 root root 117960 Nov 27 21:10 ld-2.13.so
lrwxrwxrwx 1 root root 12 Nov 27 21:41 ld-linux.so.2 -> ld-2.11.2.so
-rwxr-xr-x 1 root root 1319176 Nov 27 20:31 libc-2.11.2.so
-rwxr-xr-x 1 root root 1314952 Nov 27 21:40 libc-2.13.so
lrwxrwxrwx 1 root root 12 Nov 27 21:40 libc.so.6 -> libc-2.13.so
0 root@stylus:/tmp# chroot x /bin/true
0 root@stylus:/tmp#
I'm sorry i don't know how to solve this problem, but i'd be happy to
see it re-assigned to a different package (eglibc?) if you think that
would help move it toward a resolution.
If you want more debugging info, just let me know.
Regards,
--dkg
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