Jiayuan Chen b40cc5adaa bpf, sockmap: Fix incorrect copied_seq calculation
A socket using sockmap has its own independent receive queue: ingress_msg.
This queue may contain data from its own protocol stack or from other
sockets.

The issue is that when reading from ingress_msg, we update tp->copied_seq
by default. However, if the data is not from its own protocol stack,
tcp->rcv_nxt is not increased. Later, if we convert this socket to a
native socket, reading from this socket may fail because copied_seq might
be significantly larger than rcv_nxt.

This fix also addresses the syzkaller-reported bug referenced in the
Closes tag.

This patch marks the skmsg objects in ingress_msg. When reading, we update
copied_seq only if the data is from its own protocol stack.

                                                     FD1:read()
                                                     --  FD1->copied_seq++
                                                         |  [read data]
                                                         |
                                [enqueue data]           v
                  [sockmap]     -> ingress to self ->  ingress_msg queue
FD1 native stack  ------>                                 ^
-- FD1->rcv_nxt++               -> redirect to other      | [enqueue data]
                                       |                  |
                                       |             ingress to FD1
                                       v                  ^
                                      ...                 |  [sockmap]
                                                     FD2 native stack

Closes: https://syzkaller.appspot.com/bug?extid=06dbd397158ec0ea4983
Fixes: 04919bed94 ("tcp: Introduce tcp_read_skb()")
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Link: https://lore.kernel.org/r/20260124113314.113584-2-jiayuan.chen@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
2026-01-27 09:11:30 -08:00
2026-01-11 06:09:11 -10:00
2022-09-28 09:02:20 +02:00
2026-01-11 06:09:11 -10:00
2025-02-19 14:53:27 -07:00

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

The Linux kernel is the core of any Linux operating system. It manages hardware,
system resources, and provides the fundamental services for all other software.

Quick Start
-----------

* Report a bug: See Documentation/admin-guide/reporting-issues.rst
* Get the latest kernel: https://kernel.org
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* Join the community: https://lore.kernel.org/

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-----------------------

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* Building requirements: Documentation/process/changes.rst
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============

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For Specific Users
==================

New Kernel Developer
--------------------

Welcome! Start your kernel development journey here:

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-------------------

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* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
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* Networking Stack: Documentation/networking/index.rst
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---------------

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-----------------------------

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* Git for Maintainers: Documentation/maintainer/configure-git.rst

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--------------------

Configure, tune, and troubleshoot Linux systems:

* Admin Guide: Documentation/admin-guide/index.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst
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----------

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---------------

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* Driver API Guide: Documentation/driver-api/index.rst
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* DMA API: Documentation/core-api/dma-api.rst

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-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
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=========================

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