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Eric Dumazet 151c9c724d tcp: properly terminate timers for kernel sockets
We had various syzbot reports about tcp timers firing after
the corresponding netns has been dismantled.

Fortunately Josef Bacik could trigger the issue more often,
and could test a patch I wrote two years ago.

When TCP sockets are closed, we call inet_csk_clear_xmit_timers()
to 'stop' the timers.

inet_csk_clear_xmit_timers() can be called from any context,
including when socket lock is held.
This is the reason it uses sk_stop_timer(), aka del_timer().
This means that ongoing timers might finish much later.

For user sockets, this is fine because each running timer
holds a reference on the socket, and the user socket holds
a reference on the netns.

For kernel sockets, we risk that the netns is freed before
timer can complete, because kernel sockets do not hold
reference on the netns.

This patch adds inet_csk_clear_xmit_timers_sync() function
that using sk_stop_timer_sync() to make sure all timers
are terminated before the kernel socket is released.
Modules using kernel sockets close them in their netns exit()
handler.

Also add sock_not_owned_by_me() helper to get LOCKDEP
support : inet_csk_clear_xmit_timers_sync() must not be called
while socket lock is held.

It is very possible we can revert in the future commit
3a58f13a88 ("net: rds: acquire refcount on TCP sockets")
which attempted to solve the issue in rds only.
(net/smc/af_smc.c and net/mptcp/subflow.c have similar code)

We probably can remove the check_net() tests from
tcp_out_of_resources() and __tcp_close() in the future.

Reported-by: Josef Bacik <josef@toxicpanda.com>
Closes: https://lore.kernel.org/netdev/20240314210740.GA2823176@perftesting/
Fixes: 26abe14379 ("net: Modify sk_alloc to not reference count the netns of kernel sockets.")
Fixes: 8a68173691 ("net: sk_clone_lock() should only do get_net() if the parent is not a kernel socket")
Link: https://lore.kernel.org/bpf/CANn89i+484ffqb93aQm1N-tjxxvb3WDKX0EbD7318RwRgsatjw@mail.gmail.com/
Signed-off-by: Eric Dumazet <edumazet@google.com>
Tested-by: Josef Bacik <josef@toxicpanda.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: https://lore.kernel.org/r/20240322135732.1535772-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
2024-03-25 19:51:57 -07:00
arch Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
block vfs-6.9-rc1.fixes 2024-03-18 09:15:50 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This update includes the following changes: 2024-03-15 14:46:54 -07:00
Documentation Including fixes from CAN, netfilter, wireguard and IPsec. 2024-03-21 14:50:39 -07:00
drivers net: ll_temac: platform_get_resource replaced by wrong function 2024-03-25 19:46:56 -07:00
fs Driver core changes for 6.9-rc1 2024-03-21 13:34:15 -07:00
include tcp: properly terminate timers for kernel sockets 2024-03-25 19:51:57 -07:00
init Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
io_uring for-6.9/io_uring-20240310 2024-03-11 11:35:31 -07:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel Including fixes from CAN, netfilter, wireguard and IPsec. 2024-03-21 14:50:39 -07:00
lib Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
net tcp: properly terminate timers for kernel sockets 2024-03-25 19:51:57 -07:00
rust Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
security - Kuan-Wei Chiu has developed the well-named series "lib min_heap: Min 2024-03-14 18:03:09 -07:00
sound TTY/Serial driver update for 6.9-rc1 2024-03-21 12:44:10 -07:00
tools tools: ynl: fix setting presence bits in simple nests 2024-03-22 17:54:38 -07:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM Xen and pfncache changes for 6.9: 2024-03-11 10:42:55 -04:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap Char/Misc and other driver subsystem updates for 6.9-rc1 2024-03-21 13:21:31 -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 Not a ton of stuff happening in the clk framework in this pull request. We got 2024-03-15 11:48:01 -07:00
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 Including fixes from CAN, netfilter, wireguard and IPsec. 2024-03-21 14:50:39 -07:00
Makefile Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -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 reStructuredText 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.