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Vladimir Murzin cfb3293c45 usb: mtu3: Fix double dereference in TP_printk
Paul reported kernel splat:

[    0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
[    0.000000] ------------[ cut here ]------------
[    0.000000] Event mtu3_gadget_ep_set_halt has double dereference in TP_printk: &REC->gpd_ring->dma
[    0.000000] WARNING: kernel/trace/trace_events.c:420 at test_double_dereference+0x144/0x14c, CPU#0: swapper/0/0
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 7.3.0-rc1 #15247 PREEMPT
[    0.000000] Hardware name: linux,dummy-virt (DT)
[    0.000000] pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[    0.000000] pc : test_double_dereference+0x144/0x14c
[    0.000000] lr : test_double_dereference+0x144/0x14c
[    0.000000] sp : ffffc80aa7633bf0
[    0.000000] x29: ffffc80aa7633bf0 x28: ffffc80aa7c0f047 x27: 000508b58019388f
[    0.000000] x26: 0000000000000003 x25: 0000000000000007 x24: ffffc80aa5fceff8
[    0.000000] x23: ffffc80aa7c0f05a x22: ffffc80aa64edfe8 x21: ffffc80aa7c0fce8
[    0.000000] x20: ffffc80aa7c0f047 x19: 0000000000000013 x18: 0000000000000001
[    0.000000] x17: 6572656420656c62 x16: 756f642073616820 x15: 746c61685f746573
[    0.000000] x14: 0000000000000000 x13: ffff000139d90000 x12: 0000000000000045
[    0.000000] x11: 00000000000000cf x10: ffff00013f546428 x9 : ffff000139d90000
[    0.000000] x8 : 3fffffffffffc000 x7 : 0000000000000001 x6 : 0000000000000001
[    0.000000] x5 : ffff00013f4e6440 x4 : 0000000000000000 x3 : 0000000000000000
[    0.000000] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffc80aa764a700
[    0.000000] Call trace:
[    0.000000]  test_double_dereference+0x144/0x14c (P)
[    0.000000]  trace_event_raw_init+0x37c/0x5d8
[    0.000000]  event_init+0x34/0xc0
[    0.000000]  trace_event_init+0xec/0x588
[    0.000000]  trace_init+0x24/0x6e0
[    0.000000]  start_kernel+0x4a0/0x8ec
[    0.000000]  __primary_switched+0x88/0x90
[    0.000000] irq event stamp: 0
[    0.000000] hardirqs last  enabled at (0): [<0000000000000000>] 0x0
[    0.000000] hardirqs last disabled at (0): [<0000000000000000>] 0x0
[    0.000000] softirqs last  enabled at (0): [<0000000000000000>] 0x0
[    0.000000] softirqs last disabled at (0): [<0000000000000000>] 0x0
[    0.000000] ---[ end trace 0000000000000000 ]---
[    0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_disable has double dereference in TP_printk: &REC->gpd_ring->dma
[    0.000000] TRACE EVENT ERROR: Event mtu3_gadget_ep_enable has double dereference in TP_printk: &REC->gpd_ring->dma

Which also observed by Mark and myself.

The splat it result of new check introduced by b5cc230af5 ("tracing:
Warn when an event dereferences a pointer in TP_printk()") which
correctly catches issue with %pad dereferencing the address saved in
the ring buffer. TP_fast_assign() logic gets executed when the
tracepoint is triggered, however the TP_printk() is executed when the
user reads the trace buffer which could be seconds, minutes, hours,
days, even months later and nothing guarantee that __entry->gpd_ring
pointer will still be pointing to what it was when it was recorded.

Fix the issue by capturing immediate value of gpd_ring.dma when trace
point is triggered.

Reported-by: Paul E. McKenney <paulmck@kernel.org>
Tested-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Vladimir Murzin <vladimir.murzin@arm.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
History 2026-09-29 17:26:50 -07:00
arch - Fix UM build regression caused by the removal of the UM 2026-08-30 10:19:11 -07:00
block for-7.3/block-20260819 2026-08-20 13:55:16 -07:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push fixes a memory allocation overrun in crypto acomp. 2026-08-28 09:28:40 -07:00
Documentation Coccinelle patches for Linux v7.3 2026-08-30 10:42:40 -07:00
drivers usb: mtu3: Fix double dereference in TP_printk 2026-09-29 17:26:50 -07:00
fs tracing fixes for v7.3: 2026-08-30 09:22:00 -07:00
include - Revert a commit to spinlock cleanup guards that got caught up 2026-08-30 09:57:35 -07:00
init Bootconfig updates for v7.3: 2026-08-25 08:59:09 -07:00
io_uring io_uring-7.3-20260828 2026-08-28 16:51:14 -07:00
ipc mm.git review status for master..mm-nonmm-stable 2026-08-23 08:07:11 -07:00
kernel - Revert a commit to spinlock cleanup guards that got caught up 2026-08-30 09:57:35 -07:00
lib mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
LICENSES LICENSES: Add modern form of the LGPL-2.1 tags to the usage guide section 2025-10-22 07:58:19 +02:00
mm mm.git review status for linus..mm-stable 2026-08-27 09:17:06 -07:00
net A wide variety of mostly CephFS fixes and cleanups, split between 2026-08-28 11:51:05 -07:00
rust Rust fixes for v7.3 2026-08-30 09:47:39 -07:00
samples tracing fixes for v7.3: 2026-08-30 09:22:00 -07:00
scripts Coccinelle patches for Linux v7.3 2026-08-30 10:42:40 -07:00
security Hi, 2026-08-28 09:36:27 -07:00
sound sound fixes for 7.3-rc1 2026-08-28 10:01:02 -07:00
tools Rust fixes for v7.3 2026-08-30 09:47:39 -07:00
usr usr: Correct a spelling by changing a letter 2026-08-05 14:51:58 +02:00
virt Arm: 2026-08-25 11:48:04 -07:00
.clang-format drm/bridge: rename drm_for_each_bridge_in_chain_scoped() to drm_for_each_bridge_in_chain() 2026-07-14 17:55:51 +02:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.editorconfig editorconfig: add rst extension 2026-01-26 19:07:09 -08:00
.get_maintainer.ignore .get_maintainer.ignore: add Nathan Chancellor 2026-08-03 21:10:12 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore SPDX patches for 7.2-rc1 2026-06-22 12:06:22 -07:00
.mailmap CREDITS/mailmap: add some info about Darrick J. Wong 2026-08-30 10:29:08 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -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 CREDITS/mailmap: add some info about Darrick J. Wong 2026-08-30 10:29:08 -07:00
Kbuild checksyscalls: move instance functionality into generic code 2026-04-05 09:21:32 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS SCSI updates for 7.3 2026-08-29 11:55:36 -07:00
Makefile Linux 7.3-rc1 2026-08-30 13:34:40 -07:00
README README: remove out of place emdashes 2026-07-15 10:51:29 -06:00

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
* Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst
* Join the community: https://lore.kernel.org/

Essential Documentation
-----------------------

All users should be familiar with:

* Building requirements: Documentation/process/changes.rst
* Code of Conduct: Documentation/process/code-of-conduct.rst
* License: See COPYING

Documentation can be built with make htmldocs or viewed online at:
https://www.kernel.org/doc/html/latest/


Who Are You?
============

Find your role below:

* New Kernel Developer: Getting started with kernel development
* Academic Researcher: Studying kernel internals and architecture
* Security Expert: Hardening and vulnerability analysis
* Backport/Maintenance Engineer: Maintaining stable kernels
* System Administrator: Configuring and troubleshooting
* Maintainer: Leading subsystems and reviewing patches
* Hardware Vendor: Writing drivers for new hardware
* Distribution Maintainer: Packaging kernels for distros
* AI Coding Assistant: LLMs and AI-powered development tools


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

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

Welcome! Start your kernel development journey here:

* Getting Started: Documentation/process/development-process.rst
* Your First Patch: Documentation/process/submitting-patches.rst
* Coding Style: Documentation/process/coding-style.rst
* Build System: Documentation/kbuild/index.rst
* Development Tools: Documentation/dev-tools/index.rst
* Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst
* Core APIs: Documentation/core-api/index.rst

Academic Researcher
-------------------

Explore the kernel's architecture and internals:

* Researcher Guidelines: Documentation/process/researcher-guidelines.rst
* Memory Management: Documentation/mm/index.rst
* Scheduler: Documentation/scheduler/index.rst
* Networking Stack: Documentation/networking/index.rst
* Filesystems: Documentation/filesystems/index.rst
* RCU (Read-Copy Update): Documentation/RCU/index.rst
* Locking Primitives: Documentation/locking/index.rst
* Power Management: Documentation/power/index.rst

Security Expert
---------------

Security documentation and hardening guides:

* Security Documentation: Documentation/security/index.rst
* LSM Development: Documentation/security/lsm-development.rst
* Self Protection: Documentation/security/self-protection.rst
* Reporting Vulnerabilities: Documentation/process/security-bugs.rst
* CVE Procedures: Documentation/process/cve.rst
* Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst
* Security Features: Documentation/userspace-api/seccomp_filter.rst

Backport/Maintenance Engineer
-----------------------------

Maintain and stabilize kernel versions:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* Backporting Guide: Documentation/process/backporting.rst
* Applying Patches: Documentation/process/applying-patches.rst
* Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git for Maintainers: Documentation/maintainer/configure-git.rst

System Administrator
--------------------

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
* Tracing/Debugging: Documentation/trace/index.rst
* Performance Security: Documentation/admin-guide/perf-security.rst
* Hardware Monitoring: Documentation/hwmon/index.rst

Maintainer
----------

Lead kernel subsystems and manage contributions:

* Maintainer Handbook: Documentation/maintainer/index.rst
* Pull Requests: Documentation/maintainer/pull-requests.rst
* Managing Patches: Documentation/maintainer/modifying-patches.rst
* Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst
* Development Process: Documentation/process/maintainer-handbooks.rst
* Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst
* Git Configuration: Documentation/maintainer/configure-git.rst

Hardware Vendor
---------------

Write drivers and support new hardware:

* Driver API Guide: Documentation/driver-api/index.rst
* Driver Model: Documentation/driver-api/driver-model/driver.rst
* Device Drivers: Documentation/driver-api/infrastructure.rst
* Bus Types: Documentation/driver-api/driver-model/bus.rst
* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

Distribution Maintainer
-----------------------

Package and distribute the kernel:

* Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst
* ABI Documentation: Documentation/ABI/README
* Kernel Configuration: Documentation/kbuild/kconfig.rst
* Module Signing: Documentation/admin-guide/module-signing.rst
* Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst
* Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst

AI Coding Assistant
-------------------

CRITICAL: If you are an LLM or AI-powered coding assistant, you MUST read and
follow the AI coding assistants documentation before contributing to the Linux
kernel:

* Documentation/process/coding-assistants.rst

This documentation contains essential requirements about licensing, attribution,
and the Developer Certificate of Origin that all AI tools must comply with.


Communication and Support
=========================

* Mailing Lists: https://lore.kernel.org/
* IRC: #kernelnewbies on irc.oftc.net
* Bugzilla: https://bugzilla.kernel.org/
* MAINTAINERS file: Lists subsystem maintainers and mailing lists
* Email Clients: Documentation/process/email-clients.rst