From: Paolo Abeni pabeni@redhat.com
MPTCP maintains the received sub-options status is the bitmask carrying the received suboptions and in several bitfields carrying per suboption additional info.
Zeroing the bitmask before parsing is not enough to ensure a consistent status, and the MPTCP code has to additionally clear some bitfiled depending on the actually parsed suboption.
The above schema is fragile, and syzbot managed to trigger a path where a relevant bitfield is not cleared/initialized:
BUG: KMSAN: uninit-value in __mptcp_expand_seq net/mptcp/options.c:1030 [inline] BUG: KMSAN: uninit-value in mptcp_expand_seq net/mptcp/protocol.h:864 [inline] BUG: KMSAN: uninit-value in ack_update_msk net/mptcp/options.c:1060 [inline] BUG: KMSAN: uninit-value in mptcp_incoming_options+0x2036/0x3d30 net/mptcp/options.c:1209 __mptcp_expand_seq net/mptcp/options.c:1030 [inline] mptcp_expand_seq net/mptcp/protocol.h:864 [inline] ack_update_msk net/mptcp/options.c:1060 [inline] mptcp_incoming_options+0x2036/0x3d30 net/mptcp/options.c:1209 tcp_data_queue+0xb4/0x7be0 net/ipv4/tcp_input.c:5233 tcp_rcv_established+0x1061/0x2510 net/ipv4/tcp_input.c:6264 tcp_v4_do_rcv+0x7f3/0x11a0 net/ipv4/tcp_ipv4.c:1916 tcp_v4_rcv+0x51df/0x5750 net/ipv4/tcp_ipv4.c:2351 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x336/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:447 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core net/core/dev.c:5704 [inline] __netif_receive_skb+0x319/0xa00 net/core/dev.c:5817 process_backlog+0x4ad/0xa50 net/core/dev.c:6149 __napi_poll+0xe7/0x980 net/core/dev.c:6902 napi_poll net/core/dev.c:6971 [inline] net_rx_action+0xa5a/0x19b0 net/core/dev.c:7093 handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561 __do_softirq+0x14/0x1a kernel/softirq.c:595 do_softirq+0x9a/0x100 kernel/softirq.c:462 __local_bh_enable_ip+0x9f/0xb0 kernel/softirq.c:389 local_bh_enable include/linux/bottom_half.h:33 [inline] rcu_read_unlock_bh include/linux/rcupdate.h:919 [inline] __dev_queue_xmit+0x2758/0x57d0 net/core/dev.c:4493 dev_queue_xmit include/linux/netdevice.h:3168 [inline] neigh_hh_output include/net/neighbour.h:523 [inline] neigh_output include/net/neighbour.h:537 [inline] ip_finish_output2+0x187c/0x1b70 net/ipv4/ip_output.c:236 __ip_finish_output+0x287/0x810 ip_finish_output+0x4b/0x600 net/ipv4/ip_output.c:324 NF_HOOK_COND include/linux/netfilter.h:303 [inline] ip_output+0x15f/0x3f0 net/ipv4/ip_output.c:434 dst_output include/net/dst.h:450 [inline] ip_local_out net/ipv4/ip_output.c:130 [inline] __ip_queue_xmit+0x1f2a/0x20d0 net/ipv4/ip_output.c:536 ip_queue_xmit+0x60/0x80 net/ipv4/ip_output.c:550 __tcp_transmit_skb+0x3cea/0x4900 net/ipv4/tcp_output.c:1468 tcp_transmit_skb net/ipv4/tcp_output.c:1486 [inline] tcp_write_xmit+0x3b90/0x9070 net/ipv4/tcp_output.c:2829 __tcp_push_pending_frames+0xc4/0x380 net/ipv4/tcp_output.c:3012 tcp_send_fin+0x9f6/0xf50 net/ipv4/tcp_output.c:3618 __tcp_close+0x140c/0x1550 net/ipv4/tcp.c:3130 __mptcp_close_ssk+0x74e/0x16f0 net/mptcp/protocol.c:2496 mptcp_close_ssk+0x26b/0x2c0 net/mptcp/protocol.c:2550 mptcp_pm_nl_rm_addr_or_subflow+0x635/0xd10 net/mptcp/pm_netlink.c:889 mptcp_pm_nl_rm_subflow_received net/mptcp/pm_netlink.c:924 [inline] mptcp_pm_flush_addrs_and_subflows net/mptcp/pm_netlink.c:1688 [inline] mptcp_nl_flush_addrs_list net/mptcp/pm_netlink.c:1709 [inline] mptcp_pm_nl_flush_addrs_doit+0xe10/0x1630 net/mptcp/pm_netlink.c:1750 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x1214/0x12c0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2542 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:726 ____sys_sendmsg+0x877/0xb60 net/socket.c:2583 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x212/0x3c0 net/socket.c:2672 x64_sys_call+0x2ed6/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at: mptcp_get_options+0x2c0f/0x2f20 net/mptcp/options.c:397 mptcp_incoming_options+0x19a/0x3d30 net/mptcp/options.c:1150 tcp_data_queue+0xb4/0x7be0 net/ipv4/tcp_input.c:5233 tcp_rcv_established+0x1061/0x2510 net/ipv4/tcp_input.c:6264 tcp_v4_do_rcv+0x7f3/0x11a0 net/ipv4/tcp_ipv4.c:1916 tcp_v4_rcv+0x51df/0x5750 net/ipv4/tcp_ipv4.c:2351 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x336/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:447 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core net/core/dev.c:5704 [inline] __netif_receive_skb+0x319/0xa00 net/core/dev.c:5817 process_backlog+0x4ad/0xa50 net/core/dev.c:6149 __napi_poll+0xe7/0x980 net/core/dev.c:6902 napi_poll net/core/dev.c:6971 [inline] net_rx_action+0xa5a/0x19b0 net/core/dev.c:7093 handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561 __do_softirq+0x14/0x1a kernel/softirq.c:595
Uninit was stored to memory at: put_unaligned_be32 include/linux/unaligned.h:68 [inline] mptcp_write_options+0x17f9/0x3100 net/mptcp/options.c:1417 mptcp_options_write net/ipv4/tcp_output.c:465 [inline] tcp_options_write+0x6d9/0xe90 net/ipv4/tcp_output.c:759 __tcp_transmit_skb+0x294b/0x4900 net/ipv4/tcp_output.c:1414 tcp_transmit_skb net/ipv4/tcp_output.c:1486 [inline] tcp_write_xmit+0x3b90/0x9070 net/ipv4/tcp_output.c:2829 __tcp_push_pending_frames+0xc4/0x380 net/ipv4/tcp_output.c:3012 tcp_send_fin+0x9f6/0xf50 net/ipv4/tcp_output.c:3618 __tcp_close+0x140c/0x1550 net/ipv4/tcp.c:3130 __mptcp_close_ssk+0x74e/0x16f0 net/mptcp/protocol.c:2496 mptcp_close_ssk+0x26b/0x2c0 net/mptcp/protocol.c:2550 mptcp_pm_nl_rm_addr_or_subflow+0x635/0xd10 net/mptcp/pm_netlink.c:889 mptcp_pm_nl_rm_subflow_received net/mptcp/pm_netlink.c:924 [inline] mptcp_pm_flush_addrs_and_subflows net/mptcp/pm_netlink.c:1688 [inline] mptcp_nl_flush_addrs_list net/mptcp/pm_netlink.c:1709 [inline] mptcp_pm_nl_flush_addrs_doit+0xe10/0x1630 net/mptcp/pm_netlink.c:1750 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x1214/0x12c0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2542 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:726 ____sys_sendmsg+0x877/0xb60 net/socket.c:2583 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x212/0x3c0 net/socket.c:2672 x64_sys_call+0x2ed6/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at: mptcp_pm_add_addr_signal+0x3d7/0x4c0 mptcp_established_options_add_addr net/mptcp/options.c:666 [inline] mptcp_established_options+0x1b9b/0x3a00 net/mptcp/options.c:884 tcp_established_options+0x2c4/0x7d0 net/ipv4/tcp_output.c:1012 __tcp_transmit_skb+0x5b7/0x4900 net/ipv4/tcp_output.c:1333 tcp_transmit_skb net/ipv4/tcp_output.c:1486 [inline] tcp_write_xmit+0x3b90/0x9070 net/ipv4/tcp_output.c:2829 __tcp_push_pending_frames+0xc4/0x380 net/ipv4/tcp_output.c:3012 tcp_send_fin+0x9f6/0xf50 net/ipv4/tcp_output.c:3618 __tcp_close+0x140c/0x1550 net/ipv4/tcp.c:3130 __mptcp_close_ssk+0x74e/0x16f0 net/mptcp/protocol.c:2496 mptcp_close_ssk+0x26b/0x2c0 net/mptcp/protocol.c:2550 mptcp_pm_nl_rm_addr_or_subflow+0x635/0xd10 net/mptcp/pm_netlink.c:889 mptcp_pm_nl_rm_subflow_received net/mptcp/pm_netlink.c:924 [inline] mptcp_pm_flush_addrs_and_subflows net/mptcp/pm_netlink.c:1688 [inline] mptcp_nl_flush_addrs_list net/mptcp/pm_netlink.c:1709 [inline] mptcp_pm_nl_flush_addrs_doit+0xe10/0x1630 net/mptcp/pm_netlink.c:1750 genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline] genl_rcv_msg+0x1214/0x12c0 net/netlink/genetlink.c:1210 netlink_rcv_skb+0x375/0x650 net/netlink/af_netlink.c:2542 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1219 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline] netlink_unicast+0xf52/0x1260 net/netlink/af_netlink.c:1347 netlink_sendmsg+0x10da/0x11e0 net/netlink/af_netlink.c:1891 sock_sendmsg_nosec net/socket.c:711 [inline] __sock_sendmsg+0x30f/0x380 net/socket.c:726 ____sys_sendmsg+0x877/0xb60 net/socket.c:2583 ___sys_sendmsg+0x28d/0x3c0 net/socket.c:2637 __sys_sendmsg net/socket.c:2669 [inline] __do_sys_sendmsg net/socket.c:2674 [inline] __se_sys_sendmsg net/socket.c:2672 [inline] __x64_sys_sendmsg+0x212/0x3c0 net/socket.c:2672 x64_sys_call+0x2ed6/0x3c30 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f
Uninit was stored to memory at: mptcp_pm_add_addr_received+0x95f/0xdd0 net/mptcp/pm.c:235 mptcp_incoming_options+0x2983/0x3d30 net/mptcp/options.c:1169 tcp_data_queue+0xb4/0x7be0 net/ipv4/tcp_input.c:5233 tcp_rcv_state_process+0x2a38/0x49d0 net/ipv4/tcp_input.c:6972 tcp_v4_do_rcv+0xbf9/0x11a0 net/ipv4/tcp_ipv4.c:1939 tcp_v4_rcv+0x51df/0x5750 net/ipv4/tcp_ipv4.c:2351 ip_protocol_deliver_rcu+0x2a3/0x13d0 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x336/0x500 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:460 [inline] ip_rcv_finish+0x4a2/0x520 net/ipv4/ip_input.c:447 NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0xcd/0x380 net/ipv4/ip_input.c:567 __netif_receive_skb_one_core net/core/dev.c:5704 [inline] __netif_receive_skb+0x319/0xa00 net/core/dev.c:5817 process_backlog+0x4ad/0xa50 net/core/dev.c:6149 __napi_poll+0xe7/0x980 net/core/dev.c:6902 napi_poll net/core/dev.c:6971 [inline] net_rx_action+0xa5a/0x19b0 net/core/dev.c:7093 handle_softirqs+0x1a0/0x7c0 kernel/softirq.c:561 __do_softirq+0x14/0x1a kernel/softirq.c:595
Local variable mp_opt created at: mptcp_incoming_options+0x119/0x3d30 net/mptcp/options.c:1127 tcp_data_queue+0xb4/0x7be0 net/ipv4/tcp_input.c:5233
The current schema is too fragile; address the issue grouping all the state-related data together and clearing the whole group instead of just the bitmask. This also cleans-up the code a bit, as there is no need to individually clear "random" bitfield in a couple of places any more.
Fixes: 84dfe3677a6f ("mptcp: send out dedicated ADD_ADDR packet") Cc: stable@vger.kernel.org Reported-by: syzbot+23728c2df58b3bd175ad@syzkaller.appspotmail.com Closes: https://lore.kernel.org/6786ac51.050a0220.216c54.00a7.GAE@google.com Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/541 Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org --- net/mptcp/options.c | 13 +++++-------- net/mptcp/protocol.h | 30 ++++++++++++++++-------------- 2 files changed, 21 insertions(+), 22 deletions(-)
diff --git a/net/mptcp/options.c b/net/mptcp/options.c index 123f3f2972841aab9fc2ef338687b4c4758efd4a..fd2de185bc939f8730e87a63ac02a015e610e99c 100644 --- a/net/mptcp/options.c +++ b/net/mptcp/options.c @@ -108,7 +108,6 @@ static void mptcp_parse_option(const struct sk_buff *skb, mp_opt->suboptions |= OPTION_MPTCP_DSS; mp_opt->use_map = 1; mp_opt->mpc_map = 1; - mp_opt->use_ack = 0; mp_opt->data_len = get_unaligned_be16(ptr); ptr += 2; } @@ -157,11 +156,6 @@ static void mptcp_parse_option(const struct sk_buff *skb, pr_debug("DSS\n"); ptr++;
- /* we must clear 'mpc_map' be able to detect MP_CAPABLE - * map vs DSS map in mptcp_incoming_options(), and reconstruct - * map info accordingly - */ - mp_opt->mpc_map = 0; flags = (*ptr++) & MPTCP_DSS_FLAG_MASK; mp_opt->data_fin = (flags & MPTCP_DSS_DATA_FIN) != 0; mp_opt->dsn64 = (flags & MPTCP_DSS_DSN64) != 0; @@ -369,8 +363,11 @@ void mptcp_get_options(const struct sk_buff *skb, const unsigned char *ptr; int length;
- /* initialize option status */ - mp_opt->suboptions = 0; + /* Ensure that casting the whole status to u32 is efficient and safe */ + BUILD_BUG_ON(sizeof_field(struct mptcp_options_received, status) != sizeof(u32)); + BUILD_BUG_ON(!IS_ALIGNED(offsetof(struct mptcp_options_received, status), + sizeof(u32))); + *(u32 *)&mp_opt->status = 0;
length = (th->doff * 4) - sizeof(struct tcphdr); ptr = (const unsigned char *)(th + 1); diff --git a/net/mptcp/protocol.h b/net/mptcp/protocol.h index 0174a5aad2796c6e943e618bb677a2baff6eab22..f6a207958459db5bd39f91ed7431b5a766669f92 100644 --- a/net/mptcp/protocol.h +++ b/net/mptcp/protocol.h @@ -149,22 +149,24 @@ struct mptcp_options_received { u32 subflow_seq; u16 data_len; __sum16 csum; - u16 suboptions; + struct_group(status, + u16 suboptions; + u16 use_map:1, + dsn64:1, + data_fin:1, + use_ack:1, + ack64:1, + mpc_map:1, + reset_reason:4, + reset_transient:1, + echo:1, + backup:1, + deny_join_id0:1, + __unused:2; + ); + u8 join_id; u32 token; u32 nonce; - u16 use_map:1, - dsn64:1, - data_fin:1, - use_ack:1, - ack64:1, - mpc_map:1, - reset_reason:4, - reset_transient:1, - echo:1, - backup:1, - deny_join_id0:1, - __unused:2; - u8 join_id; u64 thmac; u8 hmac[MPTCPOPT_HMAC_LEN]; struct mptcp_addr_info addr;