From: Lukas Wunner <lukas@xxxxxxxxx>
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@xxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v3.13+
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
include/net/netfilter/nf_tables.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/include/net/netfilter/nf_tables.h b/include/net/netfilter/nf_tables.h
index 001d294edf57..2d0275f13bbf 100644
--- a/include/net/netfilter/nf_tables.h
+++ b/include/net/netfilter/nf_tables.h
@@ -820,7 +820,8 @@ 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)
--
2.11.0
