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Paolo Abeni b2b4c84eb7 mptcp: fix disconnect vs accept race 
commit 511b90e392 upstream.

Despite commit 0ad529d9fd ("mptcp: fix possible divide by zero in
recvmsg()"), the mptcp protocol is still prone to a race between
disconnect() (or shutdown) and accept.

The root cause is that the mentioned commit checks the msk-level
flag, but mptcp_stream_accept() does acquire the msk-level lock,
as it can rely directly on the first subflow lock.

As reported by Christoph than can lead to a race where an msk
socket is accepted after that mptcp_subflow_queue_clean() releases
the listener socket lock and just before it takes destructive
actions leading to the following splat:

BUG: kernel NULL pointer dereference, address: 0000000000000012
PGD 5a4ca067 P4D 5a4ca067 PUD 37d4c067 PMD 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 2 PID: 10955 Comm: syz-executor.5 Not tainted 6.5.0-rc1-gdc7b257ee5dd #37
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.0-2.el7 04/01/2014
RIP: 0010:mptcp_stream_accept+0x1ee/0x2f0 include/net/inet_sock.h:330
Code: 0a 09 00 48 8b 1b 4c 39 e3 74 07 e8 bc 7c 7f fe eb a1 e8 b5 7c 7f fe 4c 8b 6c 24 08 eb 05 e8 a9 7c 7f fe 49 8b 85 d8 09 00 00 <0f> b6 40 12 88 44 24 07 0f b6 6c 24 07 bf 07 00 00 00 89 ee e8 89
RSP: 0018:ffffc90000d07dc0 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888037e8d020 RCX: ffff88803b093300
RDX: 0000000000000000 RSI: ffffffff833822c5 RDI: ffffffff8333896a
RBP: 0000607f82031520 R08: ffff88803b093300 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000003e83 R12: ffff888037e8d020
R13: ffff888037e8c680 R14: ffff888009af7900 R15: ffff888009af6880
FS:  00007fc26d708640(0000) GS:ffff88807dd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000012 CR3: 0000000066bc5001 CR4: 0000000000370ee0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 do_accept+0x1ae/0x260 net/socket.c:1872
 __sys_accept4+0x9b/0x110 net/socket.c:1913
 __do_sys_accept4 net/socket.c:1954 [inline]
 __se_sys_accept4 net/socket.c:1951 [inline]
 __x64_sys_accept4+0x20/0x30 net/socket.c:1951
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x47/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8

Address the issue by temporary removing the pending request socket
from the accept queue, so that racing accept() can't touch them.

After depleting the msk - the ssk still exists, as plain TCP sockets,
re-insert them into the accept queue, so that later inet_csk_listen_stop()
will complete the tcp socket disposal.

Fixes: 2a6a870e44 ("mptcp: stops worker on unaccepted sockets at listener close")
Cc: stable@vger.kernel.org
Reported-by: Christoph Paasch <cpaasch@apple.com>
Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/423
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Link: https://lore.kernel.org/r/20230803-upstream-net-20230803-misc-fixes-6-5-v1-4-6671b1ab11cc@tessares.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2023-08-16 18:32:17 +02:00
arch KVM: SEV: only access GHCB fields once 2023-08-16 18:32:16 +02:00
block blk-mq: Fix stall due to recursive flush plug 2023-08-03 10:25:41 +02:00
certs KEYS: Add missing function documentation 2023-04-24 16:15:52 +03:00
crypto crypto: jitter - correct health test during initialization 2023-07-19 16:36:19 +02:00
Documentation Documentation: kdump: Add va_kernel_pa_offset for RISCV64 2023-08-11 12:14:19 +02:00
drivers mmc: sdhci-f-sdh30: Replace with sdhci_pltfm 2023-08-16 18:32:16 +02:00
fs ksmbd: fix wrong next length validation of ea buffer in smb2_set_ea() 2023-08-16 18:32:16 +02:00
include tpm: Disable RNG for all AMD fTPMs 2023-08-16 18:32:16 +02:00
init init, x86: Move mem_encrypt_init() into arch_cpu_finalize_init() 2023-08-08 20:04:49 +02:00
io_uring io_uring: annotate offset timeout races 2023-08-11 12:14:26 +02:00
ipc Merge branch 'work.namespace' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2023-02-24 19:20:07 -08:00
kernel bpf: Disable preemption in bpf_event_output 2023-08-11 12:14:22 +02:00
lib debugobjects: Recheck debug_objects_enabled before reporting 2023-08-11 12:14:25 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm/gup: do not return 0 from pin_user_pages_fast() for bad args 2023-08-11 12:14:25 +02:00
net mptcp: fix disconnect vs accept race 2023-08-16 18:32:17 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:14:18 +02:00
samples samples: ftrace: Save required argument registers in sample trampolines 2023-07-23 13:54:09 +02:00
scripts kbuild: rust: avoid creating temporary files 2023-07-27 08:57:06 +02:00
security security: keys: Modify mismatched function name 2023-07-27 08:56:59 +02:00
sound ASoC: wm8904: Fill the cache for WM8904_ADC_TEST_0 register 2023-08-03 10:26:12 +02:00
tools selftests: mptcp: join: fix 'implicit EP' test 2023-08-16 18:32:17 +02:00
usr initramfs: Check negative timestamp to prevent broken cpio archive 2023-04-16 17:37:01 +09:00
virt KVM: Grab a reference to KVM for VM and vCPU stats file descriptors 2023-08-03 10:26:01 +02:00
.clang-format cxl for v6.4 2023-04-30 11:51:51 -07:00
.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 *.dtso files 2023-02-26 15:28:23 +09:00
.gitignore linux-kselftest-kunit-6.4-rc1 2023-04-24 12:31:32 -07:00
.mailmap mailmap: add entries for Ben Dooks 2023-06-19 13:19:35 -07:00
.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: sctp: move Neil to CREDITS 2023-05-12 08:51:32 +01:00
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 Networking fixes for 6.4-rc8, including fixes from ipsec, bpf, 2023-06-22 17:59:51 -07:00
Makefile Linux 6.4.10 2023-08-11 12:14:29 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.