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Wang Hai e8352f7e1e tcp: Defer ts_recent changes until req is owned 
[ Upstream commit 8d52da23b6 ]

Recently a bug was discovered where the server had entered TCP_ESTABLISHED
state, but the upper layers were not notified.

The same 5-tuple packet may be processed by different CPUSs, so two
CPUs may receive different ack packets at the same time when the
state is TCP_NEW_SYN_RECV.

In that case, req->ts_recent in tcp_check_req may be changed concurrently,
which will probably cause the newsk's ts_recent to be incorrectly large.
So that tcp_validate_incoming will fail. At this point, newsk will not be
able to enter the TCP_ESTABLISHED.

cpu1                                    cpu2
tcp_check_req
                                        tcp_check_req
 req->ts_recent = rcv_tsval = t1
                                         req->ts_recent = rcv_tsval = t2

 syn_recv_sock
  tcp_sk(child)->rx_opt.ts_recent = req->ts_recent = t2 // t1 < t2
tcp_child_process
 tcp_rcv_state_process
  tcp_validate_incoming
   tcp_paws_check
    if ((s32)(rx_opt->ts_recent - rx_opt->rcv_tsval) <= paws_win)
        // t2 - t1 > paws_win, failed
                                        tcp_v4_do_rcv
                                         tcp_rcv_state_process
                                         // TCP_ESTABLISHED

The cpu2's skb or a newly received skb will call tcp_v4_do_rcv to get
the newsk into the TCP_ESTABLISHED state, but at this point it is no
longer possible to notify the upper layer application. A notification
mechanism could be added here, but the fix is more complex, so the
current fix is used.

In tcp_check_req, req->ts_recent is used to assign a value to
tcp_sk(child)->rx_opt.ts_recent, so removing the change in req->ts_recent
and changing tcp_sk(child)->rx_opt.ts_recent directly after owning the
req fixes this bug.

Fixes: 1da177e4c3 ("Linux-2.6.12-rc2")
Signed-off-by: Wang Hai <wanghai38@huawei.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2025-03-07 16:45:41 +01:00
arch x86/cpu/kvm: SRSO: Fix possible missing IBPB on VM-Exit 2025-02-27 04:10:54 -08:00
block partitions: mac: fix handling of bogus partition table 2025-02-21 13:57:18 +01:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: ecc - Prevent ecc_digits_from_bytes from reading too many bytes 2025-01-09 13:31:52 +01:00
Documentation strparser: Add read_sock callback 2025-02-27 04:10:50 -08:00
drivers ice: Fix deinitializing VF in error path 2025-03-07 16:45:41 +01:00
fs afs: Fix the server_list to unuse a displaced server rather than putting it 2025-03-07 16:45:38 +01:00
include ipv4: Convert ip_route_input() to dscp_t. 2025-03-07 16:45:39 +01:00
init Compiler Attributes: disable __counted_by for clang < 19.1.3 2024-12-09 10:32:46 +01:00
io_uring io_uring: prevent opcode speculation 2025-02-27 04:10:51 -08:00
ipc ipc: fix memleak if msg_init_ns failed in create_ipc_ns 2024-12-09 10:32:54 +01:00
kernel ftrace: Do not add duplicate entries in subops manager ops 2025-02-27 04:10:53 -08:00
lib lib/iov_iter: fix import_iovec_ubuf iovec management 2025-02-27 04:10:52 -08:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm,madvise,hugetlb: check for 0-length range after end address adjustment 2025-02-27 04:10:52 -08:00
net tcp: Defer ts_recent changes until req is owned 2025-03-07 16:45:41 +01:00
rust rust: init: use explicit ABI to clean warning in future compilers 2025-02-17 09:40:27 +01:00
samples samples/landlock: Fix possible NULL dereference in parse_path() 2025-02-08 09:51:57 +01:00
scripts scripts/gdb: fix aarch64 userspace detection in get_current_task 2025-02-17 09:40:39 +01:00
security tomoyo: don't emit warning in tomoyo_write_control() 2025-02-17 09:40:07 +01:00
sound ALSA: hda/realtek: Fix wrong mic setup for ASUS VivoBook 15 2025-03-07 16:45:40 +01:00
tools selftests: rtnetlink: update netdevsim ipsec output format 2025-02-21 13:57:25 +01:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.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: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.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 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 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 kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.80 2025-02-27 04:10:54 -08:00
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.