/* Copyright 2011-2014 Autronica Fire and Security AS * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the Free * Software Foundation; either version 2 of the License, or (at your option) * any later version. * * Author(s): * 2011-2014 Arvid Brodin, arvid.brodin@alten.se */ #ifndef __HSR_NETLINK_H #define __HSR_NETLINK_H #include #include #include struct hsr_priv; struct hsr_port; int __init hsr_netlink_init(void); void __exit hsr_netlink_exit(void); void hsr_nl_ringerror(struct hsr_priv *hsr, unsigned char addr[ETH_ALEN], struct hsr_port *port); void hsr_nl_nodedown(struct hsr_priv *hsr, unsigned char addr[ETH_ALEN]); void hsr_nl_framedrop(int dropcount, int dev_idx); void hsr_nl_linkdown(int dev_idx); #endif /* __HSR_NETLINK_H */ 1986353705b44d9503e6bb079f4f'/> net-next plumbingsTobias Klauser
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authorEric W. Biederman <ebiederm@xmission.com>2012-12-28 18:58:39 -0800
committerEric W. Biederman <ebiederm@xmission.com>2013-01-26 22:11:41 -0800
commitc61a2810a2161986353705b44d9503e6bb079f4f (patch)
tree1f949f359d0344c2a47c8d0c597815aceb8091c0 /kernel
parent923c7538236564c46ee80c253a416705321f13e3 (diff)
userns: Avoid recursion in put_user_ns
When freeing a deeply nested user namespace free_user_ns calls put_user_ns on it's parent which may in turn call free_user_ns again. When -fno-optimize-sibling-calls is passed to gcc one stack frame per user namespace is left on the stack, potentially overflowing the kernel stack. CONFIG_FRAME_POINTER forces -fno-optimize-sibling-calls so we can't count on gcc to optimize this code. Remove struct kref and use a plain atomic_t. Making the code more flexible and easier to comprehend. Make the loop in free_user_ns explict to guarantee that the stack does not overflow with CONFIG_FRAME_POINTER enabled. I have tested this fix with a simple program that uses unshare to create a deeply nested user namespace structure and then calls exit. With 1000 nesteuser namespaces before this change running my test program causes the kernel to die a horrible death. With 10,000,000 nested user namespaces after this change my test program runs to completion and causes no harm. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Pointed-out-by: Vasily Kulikov <segoon@openwall.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Diffstat (limited to 'kernel')