linux-kernel - binfmt_misc takes precedence over binfmt

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Message-Id: <200909150428.n8F4SIGt023997@int-mx08.intmail.prod.int.phx2.redhat.com>
Date:	Tue, 15 Sep 2009 00:28:17 -0400
From:	Chuck Ebbert <cebbert@...hat.com>
To:	Ivan Kokshaysky <ink@...assic.park.msu.ru>
Cc:	<linux-kernel@...r.kernel.org>
Subject: binfmt_misc takes precedence over binfmt_script in 2.6.30

Steps to Reproduce:

mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
echo ':xyzzy:E::xyzzy::/usr/bin/stat:' > /proc/sys/fs/binfmt_misc/register
echo '#!/bin/cat' > /tmp/test.xyzzy
chmod +x /tmp/test.xyzzy
/tmp/test.xyzzy

Actual results:
The test prints the output of /usr/bin/stat /tmp/test.xyzzy

Expected results:
The test prints "#!/bin/cat".

This appears to have changed in the upstream git commit 74641f5 "alpha:
binfmt_aout fix". The commit message for that commit says "Fixed by changing
the registration order of the default binfmt handlers using list_add_tail() and
introducing insert_binfmt() function which places new handler on the top of the
binfmt list.  This might be generally useful for installing arch-specific
frontends for default handlers or just for overriding them."

It's not clear that the new behavior is worse or better, but it's a
regression and should at the very least be documented.  
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