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Matthieu Baerts (NGI0) 22b0734c94 mptcp: pm: only set fullmesh for subflow endp
commit 1bb0d13485 upstream.

With the in-kernel path-manager, it is possible to change the 'fullmesh'
flag. The code in mptcp_pm_nl_fullmesh() expects to change it only on
'subflow' endpoints, to recreate more or less subflows using the linked
address.

Unfortunately, the set_flags() hook was a bit more permissive, and
allowed 'implicit' endpoints to get the 'fullmesh' flag while it is not
allowed before.

That's what syzbot found, triggering the following warning:

  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 __mark_subflow_endp_available net/mptcp/pm_netlink.c:1496 [inline]
  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_pm_nl_fullmesh net/mptcp/pm_netlink.c:1980 [inline]
  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_nl_set_flags net/mptcp/pm_netlink.c:2003 [inline]
  WARNING: CPU: 0 PID: 6499 at net/mptcp/pm_netlink.c:1496 mptcp_pm_nl_set_flags+0x974/0xdc0 net/mptcp/pm_netlink.c:2064
  Modules linked in:
  CPU: 0 UID: 0 PID: 6499 Comm: syz.1.413 Not tainted 6.13.0-rc5-syzkaller-00172-gd1bf27c4e176 #0
  Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
  RIP: 0010:__mark_subflow_endp_available net/mptcp/pm_netlink.c:1496 [inline]
  RIP: 0010:mptcp_pm_nl_fullmesh net/mptcp/pm_netlink.c:1980 [inline]
  RIP: 0010:mptcp_nl_set_flags net/mptcp/pm_netlink.c:2003 [inline]
  RIP: 0010:mptcp_pm_nl_set_flags+0x974/0xdc0 net/mptcp/pm_netlink.c:2064
  Code: 01 00 00 49 89 c5 e8 fb 45 e8 f5 e9 b8 fc ff ff e8 f1 45 e8 f5 4c 89 f7 be 03 00 00 00 e8 44 1d 0b f9 eb a0 e8 dd 45 e8 f5 90 <0f> 0b 90 e9 17 ff ff ff 89 d9 80 e1 07 38 c1 0f 8c c9 fc ff ff 48
  RSP: 0018:ffffc9000d307240 EFLAGS: 00010293
  RAX: ffffffff8bb72e03 RBX: 0000000000000000 RCX: ffff88807da88000
  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
  RBP: ffffc9000d307430 R08: ffffffff8bb72cf0 R09: 1ffff1100b842a5e
  R10: dffffc0000000000 R11: ffffed100b842a5f R12: ffff88801e2e5ac0
  R13: ffff88805c214800 R14: ffff88805c2152e8 R15: 1ffff1100b842a5d
  FS:  00005555619f6500(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 0000000020002840 CR3: 00000000247e6000 CR4: 00000000003526f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
  Call Trace:
   <TASK>
   genl_family_rcv_msg_doit net/netlink/genetlink.c:1115 [inline]
   genl_family_rcv_msg net/netlink/genetlink.c:1195 [inline]
   genl_rcv_msg+0xb14/0xec0 net/netlink/genetlink.c:1210
   netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2542
   genl_rcv+0x28/0x40 net/netlink/genetlink.c:1219
   netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
   netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347
   netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891
   sock_sendmsg_nosec net/socket.c:711 [inline]
   __sock_sendmsg+0x221/0x270 net/socket.c:726
   ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583
   ___sys_sendmsg net/socket.c:2637 [inline]
   __sys_sendmsg+0x269/0x350 net/socket.c:2669
   do_syscall_x64 arch/x86/entry/common.c:52 [inline]
   do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
   entry_SYSCALL_64_after_hwframe+0x77/0x7f
  RIP: 0033:0x7f5fe8785d29
  Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
  RSP: 002b:00007fff571f5558 EFLAGS: 00000246 ORIG_RAX: 000000000000002e
  RAX: ffffffffffffffda RBX: 00007f5fe8975fa0 RCX: 00007f5fe8785d29
  RDX: 0000000000000000 RSI: 0000000020000480 RDI: 0000000000000007
  RBP: 00007f5fe8801b08 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
  R13: 00007f5fe8975fa0 R14: 00007f5fe8975fa0 R15: 00000000000011f4
   </TASK>

Here, syzbot managed to set the 'fullmesh' flag on an 'implicit' and
used -- according to 'id_avail_bitmap' -- endpoint, causing the PM to
try decrement the local_addr_used counter which is only incremented for
the 'subflow' endpoint.

Note that 'no type' endpoints -- not 'subflow', 'signal', 'implicit' --
are fine, because their ID will not be marked as used in the 'id_avail'
bitmap, and setting 'fullmesh' can help forcing the creation of subflow
when receiving an ADD_ADDR.

Fixes: 73c762c1f0 ("mptcp: set fullmesh flag in pm_netlink")
Cc: stable@vger.kernel.org
Reported-by: syzbot+cd16e79c1e45f3fe0377@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/6786ac51.050a0220.216c54.00a6.GAE@google.com
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/540
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20250123-net-mptcp-syzbot-issues-v1-2-af73258a726f@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ Conflicts in pm_netlink.c, because the code has been moved around in
  commit 6a42477fe4 ("mptcp: update set_flags interfaces"), but the
  same fix can still be applied at the original place. ]
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2025-02-21 13:49:54 +01:00
arch MIPS: ftrace: Declare ftrace_get_parent_ra_addr() as static 2025-02-21 13:49:54 +01:00
block block: don't revert iter for -EIOCBQUEUED 2025-02-21 13:49:45 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Add crypto_clone_tfm 2024-12-14 19:53:51 +01:00
Documentation kconfig: add warn-unknown-symbols sanity check 2025-02-21 13:49:24 +01:00
drivers gpio: xilinx: remove excess kernel doc 2025-02-21 13:49:54 +01:00
fs cachefiles: Fix NULL pointer dereference in object->file 2025-02-21 13:49:54 +01:00
include rv: Reset per-task monitors also for idle tasks 2025-02-21 13:49:47 +01:00
init initramfs: avoid filename buffer overrun 2024-12-14 19:53:14 +01:00
io_uring io_uring/rw: commit provided buffer state on async 2025-02-21 13:49:53 +01:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-14 19:54:06 +01:00
kernel printk: Fix signed integer overflow when defining LOG_BUF_LEN_MAX 2025-02-21 13:49:30 +01:00
lib lockdep: Fix upper limit for LOCKDEP_*_BITS configs 2025-02-21 13:49:29 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: kmemleak: fix upper boundary check for physical address objects 2025-02-21 13:49:49 +01:00
net mptcp: pm: only set fullmesh for subflow endp 2025-02-21 13:49:54 +01:00
rust rust: macros: provide correct provenance when constructing THIS_MODULE 2024-10-17 15:22:24 +02:00
samples samples/landlock: Fix possible NULL dereference in parse_path() 2025-02-21 13:49:03 +01:00
scripts kbuild: Move -Wenum-enum-conversion to W=2 2025-02-21 13:49:46 +01:00
security tomoyo: don't emit warning in tomoyo_write_control() 2025-02-21 13:49:31 +01:00
sound ALSA: hda: Fix headset detection failure due to unstable sort 2025-02-21 13:49:45 +01:00
tools rtla/timerlat_top: Stop timerlat tracer on signal 2025-02-21 13:49:53 +01:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:46:21 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-17 15:21:15 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add leah to 6.1 MAINTAINERS file 2024-05-17 11:56:16 +02:00
Makefile kbuild: switch from lz4c to lz4 for compression 2025-02-21 13:49:25 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.