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Kuniyuki Iwashima ff149e92ee selftest: Don't reuse port for SO_INCOMING_CPU test.
[ Upstream commit 97de5a15ed ]

Jakub reported that ASSERT_EQ(cpu, i) in so_incoming_cpu.c seems to
fire somewhat randomly.

  # #  RUN           so_incoming_cpu.before_reuseport.test3 ...
  # # so_incoming_cpu.c:191:test3:Expected cpu (32) == i (0)
  # # test3: Test terminated by assertion
  # #          FAIL  so_incoming_cpu.before_reuseport.test3
  # not ok 3 so_incoming_cpu.before_reuseport.test3

When the test failed, not-yet-accepted CLOSE_WAIT sockets received
SYN with a "challenging" SEQ number, which was sent from an unexpected
CPU that did not create the receiver.

The test basically does:

  1. for each cpu:
    1-1. create a server
    1-2. set SO_INCOMING_CPU

  2. for each cpu:
    2-1. set cpu affinity
    2-2. create some clients
    2-3. let clients connect() to the server on the same cpu
    2-4. close() clients

  3. for each server:
    3-1. accept() all child sockets
    3-2. check if all children have the same SO_INCOMING_CPU with the server

The root cause was the close() in 2-4. and net.ipv4.tcp_tw_reuse.

In a loop of 2., close() changed the client state to FIN_WAIT_2, and
the peer transitioned to CLOSE_WAIT.

In another loop of 2., connect() happened to select the same port of
the FIN_WAIT_2 socket, and it was reused as the default value of
net.ipv4.tcp_tw_reuse is 2.

As a result, the new client sent SYN to the CLOSE_WAIT socket from
a different CPU, and the receiver's sk_incoming_cpu was overwritten
with unexpected CPU ID.

Also, the SYN had a different SEQ number, so the CLOSE_WAIT socket
responded with Challenge ACK.  The new client properly returned RST
and effectively killed the CLOSE_WAIT socket.

This way, all clients were created successfully, but the error was
detected later by 3-2., ASSERT_EQ(cpu, i).

To avoid the failure, let's make sure that (i) the number of clients
is less than the number of available ports and (ii) such reuse never
happens.

Fixes: 6df96146b2 ("selftest: Add test for SO_INCOMING_CPU.")
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Tested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20240120031642.67014-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2024-01-31 16:19:02 -08:00
arch LoongArch/smp: Call rcutree_report_cpu_starting() earlier 2024-01-31 16:18:57 -08:00
block block: ensure we hold a queue reference when using queue limits 2024-01-25 15:35:57 -08:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: api - Disallow identical driver names 2024-01-31 16:18:49 -08:00
Documentation dt-bindings: net: snps,dwmac: Tx coe unsupported 2024-01-31 16:18:58 -08:00
drivers net: micrel: Fix PTP frame parsing for lan8814 2024-01-31 16:19:01 -08:00
fs afs: Hide silly-rename files from userspace 2024-01-31 16:19:01 -08:00
include udp: fix busy polling 2024-01-31 16:19:01 -08:00
init rootfs: Fix support for rootfstype= when root= is given 2024-01-25 15:35:46 -08:00
io_uring io_uring: adjust defer tw counting 2024-01-25 15:36:00 -08:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel tracing: Ensure visibility when inserting an element into tracing_map 2024-01-31 16:19:01 -08:00
lib crypto: lib/mpi - Fix unexpected pointer access in mpi_ec_init 2024-01-31 16:18:49 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: page_alloc: unreserve highatomic page blocks before oom 2024-01-31 16:18:57 -08:00
net tcp: Add memory barrier to tcp_push() 2024-01-31 16:19:02 -08:00
rust rust: Ignore preserve-most functions 2024-01-25 15:35:41 -08:00
samples vfio/mtty: Overhaul mtty interrupt handling 2024-01-10 17:16:55 +01:00
scripts scripts/get_abi: fix source path leak 2024-01-31 16:18:55 -08:00
security lsm: new security_file_ioctl_compat() hook 2024-01-31 16:18:54 -08:00
sound soundwire: fix initializing sysfs for same devices on different buses 2024-01-31 16:18:47 -08:00
tools selftest: Don't reuse port for SO_INCOMING_CPU test. 2024-01-31 16:19:02 -08:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml
COPYING
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig
MAINTAINERS Char/Misc driver fixes for 6.6-final 2023-10-28 07:51:27 -10:00
Makefile Linux 6.6.14 2024-01-25 15:36:01 -08:00
README

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

There are several guides for kernel developers and users. These guides can
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There are various text files in the Documentation/ subdirectory,
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