linux-kernel - mm-search_binary_handler-mem-limit-fix is horribly broken

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Message-ID: <20070131173656.GA5789@ccure.user-mode-linux.org>
Date:	Wed, 31 Jan 2007 12:38:06 -0500
From:	Jeff Dike <jdike@...toit.com>
To:	unlisted-recipients:; (no To-header on input)
Cc:	linux-kernel@...r.kernel.org
Subject: mm-search_binary_handler-mem-limit-fix is horribly broken

It works on i386 only by accident, and doesn't work at all with UML.

start_thread, which is called from inside the set_fs(USER_DS) -
set_fs(oldfs) does set_fs(USER_DS).  That is then blown away by the
set_fs(oldfs).

A one-line fix might be

Index: linux-2.6.17/fs/exec.c
===================================================================
--- linux-2.6.17.orig/fs/exec.c 2007-01-31 12:10:08.000000000 -0500
+++ linux-2.6.17/fs/exec.c      2007-01-31 12:41:15.000000000 -0500
@@ -1079,6 +1079,7 @@ int search_binary_handler(struct linux_b
                                continue;
                        read_unlock(&binfmt_lock);
                        retval = fn(bprm, regs);
+                       oldfs = get_fs();
                        if (retval >= 0) {
                                put_binfmt(fmt);
                                allow_write_access(bprm->file);

but this seems like it's pasting one kludge on top of another.

				Jeff

-- 
Work email - jdike at linux dot intel dot com
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