From: Lukas Wunner lukas@wunner.de
commit 250367c59e6ba0d79d702a059712d66edacd4a1a upstream.
Invoking the following commands on a 32-bit architecture with strict alignment requirements (such as an ARMv7-based Raspberry Pi) results in an alignment exception:
# nft add table ip test-ip4 # nft add chain ip test-ip4 output { type filter hook output priority 0; } # nft add rule ip test-ip4 output quota 1025 bytes
Alignment trap: not handling instruction e1b26f9f at [<7f4473f8>] Unhandled fault: alignment exception (0x001) at 0xb832e824 Internal error: : 1 [#1] PREEMPT SMP ARM Hardware name: BCM2835 [<7f4473fc>] (nft_quota_do_init [nft_quota]) [<7f447448>] (nft_quota_init [nft_quota]) [<7f4260d0>] (nf_tables_newrule [nf_tables]) [<7f4168dc>] (nfnetlink_rcv_batch [nfnetlink]) [<7f416bd0>] (nfnetlink_rcv [nfnetlink]) [<8078b334>] (netlink_unicast) [<8078b664>] (netlink_sendmsg) [<8071b47c>] (sock_sendmsg) [<8071bd18>] (___sys_sendmsg) [<8071ce3c>] (__sys_sendmsg) [<8071ce94>] (sys_sendmsg)
The reason is that nft_quota_do_init() calls atomic64_set() on an atomic64_t which is only aligned to 32-bit, not 64-bit, because it succeeds struct nft_expr in memory which only contains a 32-bit pointer. Fix by aligning the nft_expr private data to 64-bit.
Fixes: 96518518cc41 ("netfilter: add nftables") Signed-off-by: Lukas Wunner lukas@wunner.de Cc: stable@vger.kernel.org # v3.13+ Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/net/netfilter/nf_tables.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/include/net/netfilter/nf_tables.h +++ b/include/net/netfilter/nf_tables.h @@ -705,7 +705,8 @@ struct nft_expr_ops { */ struct nft_expr { const struct nft_expr_ops *ops; - unsigned char data[]; + unsigned char data[] + __attribute__((aligned(__alignof__(u64)))); };
static inline void *nft_expr_priv(const struct nft_expr *expr)