netfilter: xt_nfacct: Fix alignment mismatch in xt_nfacct_match_info
authorJuliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>
Fri, 16 Aug 2019 15:02:22 +0000 (17:02 +0200)
committerPablo Neira Ayuso <pablo@netfilter.org>
Mon, 19 Aug 2019 07:34:21 +0000 (09:34 +0200)
commit89a26cd4b501e9511d3cd3d22327fc76a75a38b3
tree0a4654959d8a8518ab74a551501a27e4dba9d72f
parent14c415862c0630e01712a4eeaf6159a2b1b6d2a4
netfilter: xt_nfacct: Fix alignment mismatch in xt_nfacct_match_info

When running a 64-bit kernel with a 32-bit iptables binary, the size of
the xt_nfacct_match_info struct diverges.

    kernel: sizeof(struct xt_nfacct_match_info) : 40
    iptables: sizeof(struct xt_nfacct_match_info)) : 36

Trying to append nfacct related rules results in an unhelpful message.
Although it is suggested to look for more information in dmesg, nothing
can be found there.

    # iptables -A <chain> -m nfacct --nfacct-name <acct-object>
    iptables: Invalid argument. Run `dmesg' for more information.

This patch fixes the memory misalignment by enforcing 8-byte alignment
within the struct's first revision. This solution is often used in many
other uapi netfilter headers.

Signed-off-by: Juliana Rodrigueiro <juliana.rodrigueiro@intra2net.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
include/uapi/linux/netfilter/xt_nfacct.h
net/netfilter/xt_nfacct.c