[PATCH] lost fput in 32bit ioctl on x86-64

[PATCH] lost fput in 32bit ioctl on x86-64

This patch adds lost fput in 32bit tiocgdev ioctl on x86-64

I believe this is a security issues, since user can fget() file as many
times as he wants to. So file refcounter can be overlapped and first
fput() will free resources though there will be still structures
pointing to the file, mnt, dentry etc.
Also fput() sets f_dentry and f_vfsmnt to NULL,
so other file users will OOPS.

The oops can be done under files_lock and others, so this is really
exploitable DoS on SMP. Didn't checked it on practice actually.

Signed-Off-By: Kirill Korotaev <dev@sw.ru>
Signed-Off-By: Maxim Giryaev <gem@sw.ru>
diff --git a/arch/x86_64/ia32/ia32_ioctl.c b/arch/x86_64/ia32/ia32_ioctl.c