linux-cve-announce - CVE-2025-21707: mptcp: consolidate suboption status

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Message-ID: <2025022643-CVE-2025-21707-2961@gregkh>
Date: Wed, 26 Feb 2025 18:06:02 -0800
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21707: mptcp: consolidate suboption status

Description
===========

In the Linux kernel, the following vulnerability has been resolved:

mptcp: consolidate suboption status

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.

The Linux kernel CVE team has assigned CVE-2025-21707 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.11 with commit 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and fixed in 6.1.129 with commit 3b5332d416d151a15742d1b16e7319368e3cc5c6
	Issue introduced in 5.11 with commit 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and fixed in 6.6.76 with commit 7f6c72b8ef8130760710e337dc8fbe7263954884
	Issue introduced in 5.11 with commit 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and fixed in 6.12.13 with commit 6169e942370b4b6f9442d35c51519bf6c346843b
	Issue introduced in 5.11 with commit 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and fixed in 6.13.2 with commit ba0518f9e8688cd4fcb569e8df2a74874b4f3894
	Issue introduced in 5.11 with commit 84dfe3677a6f45b3d0dfdd564e55717a1a5e60cc and fixed in 6.14-rc1 with commit c86b000782daba926c627d2fa00c3f60a75e7472

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2025-21707
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	net/mptcp/options.c
	net/mptcp/protocol.h


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/3b5332d416d151a15742d1b16e7319368e3cc5c6
	https://git.kernel.org/stable/c/7f6c72b8ef8130760710e337dc8fbe7263954884
	https://git.kernel.org/stable/c/6169e942370b4b6f9442d35c51519bf6c346843b
	https://git.kernel.org/stable/c/ba0518f9e8688cd4fcb569e8df2a74874b4f3894
	https://git.kernel.org/stable/c/c86b000782daba926c627d2fa00c3f60a75e7472