From: David Wilder <dwilder@us.ibm.com>
To: netdev@vger.kernel.org
Cc: netfilter-devel@vger.kernel.org, fw@strlen.de, wilder@us.ibm.com,
mkubecek@suse.com
Subject: [PATCH v1 0/4] iptables: Module unload causing NULL pointer reference.
Date: Mon, 22 Jun 2020 10:10:10 -0700 [thread overview]
Message-ID: <20200622171014.975-1-dwilder@us.ibm.com> (raw)
A crash happened on ppc64le when running ltp network tests triggered by "rmmod iptable_mangle".
See previous discussion in this thread: https://lists.openwall.net/netdev/2020/06/03/161 .
In the crash I found in iptable_mangle_hook() that state->net->ipv4.iptable_mangle=NULL causing a NULL pointer dereference. net->ipv4.iptable_mangle is set to NULL in iptable_mangle_net_exit() and called when ip_mangle modules is unloaded. A rmmod task was found running in the crash dump. A 2nd crash showed the same problem when running "rmmod iptable_filter" (net->ipv4.iptable_filter=NULL).
To fix this I added .pre_exit hook in all iptable_foo.c. The pre_exit will un-register the underlying hook and exit would do the table freeing. The netns core does an unconditional synchronize_rcu after the pre_exit hooks insuring no packets are in flight that have picked up the pointer before completing the un-register.
These patches include changes for both iptables and ip6tables.
We tested this fix with ltp running iptables01.sh and iptables01.sh -6 a loop for 72 hours.
Signed-off-by: David Wilder <dwilder@us.ibm.com>
David Wilder (4):
netfilter: Split ipt_unregister_table() into pre_exit and exit
helpers.
netfilter: Add a .pre_exit hook in all iptable_foo.c.
netfilter: Split ip6t_unregister_table() into pre_exit and exit
helpers.
netfilter: Add a .pre_exit hook in all ip6table_foo.c.
include/linux/netfilter_ipv4/ip_tables.h | 6 ++++++
include/linux/netfilter_ipv6/ip6_tables.h | 3 +++
net/ipv4/netfilter/ip_tables.c | 15 ++++++++++++++-
net/ipv4/netfilter/iptable_filter.c | 10 +++++++++-
net/ipv4/netfilter/iptable_mangle.c | 10 +++++++++-
net/ipv4/netfilter/iptable_nat.c | 10 ++++++++--
net/ipv4/netfilter/iptable_raw.c | 10 +++++++++-
net/ipv4/netfilter/iptable_security.c | 11 +++++++++--
net/ipv6/netfilter/ip6_tables.c | 15 ++++++++++++++-
net/ipv6/netfilter/ip6table_filter.c | 10 +++++++++-
net/ipv6/netfilter/ip6table_mangle.c | 10 +++++++++-
net/ipv6/netfilter/ip6table_nat.c | 10 ++++++++--
net/ipv6/netfilter/ip6table_raw.c | 10 +++++++++-
net/ipv6/netfilter/ip6table_security.c | 10 +++++++++-
14 files changed, 125 insertions(+), 15 deletions(-)
--
1.8.3.1
next reply other threads:[~2020-06-22 17:10 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-22 17:10 David Wilder [this message]
2020-06-22 17:10 ` [PATCH v1 1/4] netfilter: Split ipt_unregister_table() into pre_exit and exit helpers David Wilder
2020-06-22 17:10 ` [PATCH v1 2/4] netfilter: Add a .pre_exit hook in all iptable_foo.c David Wilder
2020-06-22 17:10 ` [PATCH v1 3/4] netfilter: Split ip6t_unregister_table() into pre_exit and exit helpers David Wilder
2020-06-22 17:10 ` [PATCH v1 4/4] netfilter: Add a .pre_exit hook in all ip6table_foo.c David Wilder
2020-06-24 12:05 ` [PATCH v1 0/4] iptables: Module unload causing NULL pointer reference Pablo Neira Ayuso
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