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Kirill Tkhai 3ff8bff704 unix: Fix race in SOCK_SEQPACKET's unix_dgram_sendmsg()
There is a race resulting in alive SOCK_SEQPACKET socket
may change its state from TCP_ESTABLISHED to TCP_CLOSE:

unix_release_sock(peer)                  unix_dgram_sendmsg(sk)
  sock_orphan(peer)
    sock_set_flag(peer, SOCK_DEAD)
                                           sock_alloc_send_pskb()
                                             if !(sk->sk_shutdown & SEND_SHUTDOWN)
                                               OK
                                           if sock_flag(peer, SOCK_DEAD)
                                             sk->sk_state = TCP_CLOSE
  sk->sk_shutdown = SHUTDOWN_MASK

After that socket sk remains almost normal: it is able to connect, listen, accept
and recvmsg, while it can't sendmsg.

Since this is the only possibility for alive SOCK_SEQPACKET to change
the state in such way, we should better fix this strange and potentially
danger corner case.

Note, that we will return EPIPE here like this is normally done in sock_alloc_send_pskb().
Originally used ECONNREFUSED looks strange, since it's strange to return
a specific retval in dependence of race in kernel, when user can't affect on this.

Also, move TCP_CLOSE assignment for SOCK_DGRAM sockets under state lock
to fix race with unix_dgram_connect():

unix_dgram_connect(other)            unix_dgram_sendmsg(sk)
                                       unix_peer(sk) = NULL
                                       unix_state_unlock(sk)
  unix_state_double_lock(sk, other)
  sk->sk_state  = TCP_ESTABLISHED
  unix_peer(sk) = other
  unix_state_double_unlock(sk, other)
                                       sk->sk_state  = TCP_CLOSED

This patch fixes both of these races.

Fixes: 83301b5367 ("af_unix: Set TCP_ESTABLISHED for datagram sockets too")
Signed-off-by: Kirill Tkhai <tkhai@ya.ru>
Link: https://lore.kernel.org/r/135fda25-22d5-837a-782b-ceee50e19844@ya.ru
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2022-12-15 11:35:18 +01:00
arch Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
block for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
certs certs: make system keyring depend on built-in x509 parser 2022-09-24 04:31:18 +09:00
crypto iov_iter work; most of that is about getting rid of 2022-12-12 18:29:54 -08:00
Documentation Merge git://git.kernel.org/pub/scm/linux/kernel/git/netfilter/nf 2022-12-13 19:32:53 -08:00
drivers nfc: pn533: Clear nfc_target before being used 2022-12-14 20:51:29 -08:00
fs EFI updates for v6.2: 2022-12-13 14:31:47 -08:00
include Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
init modules changes for v6.2-rc1 2022-12-13 14:05:39 -08:00
io_uring for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
ipc Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -08:00
kernel Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
lib Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm for-6.2/block-2022-12-08 2022-12-13 10:43:59 -08:00
net unix: Fix race in SOCK_SEQPACKET's unix_dgram_sendmsg() 2022-12-15 11:35:18 +01:00
rust rust: types: add Opaque type 2022-12-04 01:59:16 +01:00
samples Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
scripts Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
security integrity-v6.2 2022-12-13 14:22:50 -08:00
sound sound updates for 6.2-rc1 2022-12-13 11:27:26 -08:00
tools selftests: bonding: add bonding prio option test 2022-12-13 19:19:54 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt Merge branch 'kvm-dwmw2-fixes' into HEAD 2022-11-23 18:59:45 -05:00
.clang-format printk changes for 6.2 2022-12-12 09:01:36 -08:00
.cocciconfig
.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 kbuild: Cleanup DT Overlay intermediate files as appropriate 2022-11-18 14:45:30 -06:00
.mailmap Non-MM patches for 6.2-rc1. 2022-12-12 17:28:58 -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 Networking changes for 6.2. 2022-12-13 15:47:48 -08:00
Makefile This was a not-too-busy cycle for documentation; highlights include: 2022-12-12 17:18:50 -08:00
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.