Pablo Neira Ayuso says:
====================
Netfilter fixes for net
The following patchset contains Netfilter fixes for net, they are:
1) Unaligned atomic access in ipset, from Russell King.
2) Missing module description, from Rob Gill.
3) Patches to fix a module unload causing NULL pointer dereference in
xtables, from David Wilder. For the record, I posting here his cover
letter explaining the problem:
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.
4) Add a selftest for conntrack helper assignment, from Florian Westphal.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
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