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Maciek Borzecki bcd1b34c21 apparmor: fix uninitialised pointer passed to audit_log_untrustedstring()
Commit 4a134723f9 ("apparmor: move check for aa_null file to cover all cases")
intrdouced a small bug, where path_name() may pass a potentially uninitialized
*name to aa_audit_file() if the path->dentry had been replaced with
aa_null.dentry earlier on. This can lead to page fault like one observed on
7.0.2 openSUSE Tumbleweed kernel:

[51692.242756] [  T24690] BUG: unable to handle page fault for address: 0000000f00000003
[51692.242762] [  T24690] #PF: supervisor read access in kernel mode
[51692.242763] [  T24690] #PF: error_code(0x0000) - not-present page
[51692.242765] [  T24690] PGD 0 P4D 0
[51692.242768] [  T24690] Oops: Oops: 0000 [#1] SMP NOPTI
[51692.242772] [  T24690] CPU: 3 UID: 1020 PID: 24690 Comm: snap-confine Tainted: G           O        7.0.2-1-default #1 PREEMPT(full) openSUSE Tumbleweed  ab90b4c9940707f9cafa19bdad80b2cec52dbe51
[51692.242775] [  T24690] Tainted: [O]=OOT_MODULE
[51692.242777] [  T24690] Hardware name: Framework Laptop 13 (AMD Ryzen 7040Series)/FRANMDCP05, BIOS 03.18 01/08/2026
[51692.242778] [  T24690] RIP: 0010:strlen+0x4/0x30
[51692.242783] [  T24690] Code: f7 75 ec 31 c0 e9 17 9f 00 ff 48 89 f8 e9 0f 9f 00 ff 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa <80> 3f 00 74 18 48 89 f8 0f 1f 40 00 48 83 c0 01 80 38 00 75 f7 48
[51692.242785] [  T24690] RSP: 0018:ffffd015eb1e3608 EFLAGS: 00010282
[51692.242787] [  T24690] RAX: 0000000000000000 RBX: ffff89796198a360 RCX: 0000000000000000
[51692.242788] [  T24690] RDX: 00000000000000d1 RSI: 0000000f00000003 RDI: 0000000f00000003
[51692.242790] [  T24690] RBP: ffffffffb7ede090 R08: 00000000000005f5 R09: 0000000000000000
[51692.242791] [  T24690] R10: 0000000000000000 R11: 0000000000000000 R12: ffffd015eb1e3700
[51692.242792] [  T24690] R13: ffff8977a22bc380 R14: ffffffffb7ec5190 R15: ffff8977a0c8aa80
[51692.242794] [  T24690] FS:  0000000000000000(0000) GS:ffff897f640d8000(0000) knlGS:0000000000000000
[51692.242796] [  T24690] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[51692.242797] [  T24690] CR2: 0000000f00000003 CR3: 00000006ad15f000 CR4: 0000000000f50ef0
[51692.242799] [  T24690] PKRU: 55555554
[51692.242800] [  T24690] Call Trace:
[51692.242802] [  T24690]  <TASK>
[51692.242804] [  T24690]  audit_log_untrustedstring+0x1d/0x40
[51692.242811] [  T24690]  common_lsm_audit+0x71/0x1d0
[51692.242816] [  T24690]  aa_audit+0x5a/0x170
[51692.242819] [  T24690]  aa_audit_file+0x18a/0x1b0
[51692.242825] [  T24690]  path_name+0xd2/0x100
[51692.242829] [  T24690]  profile_path_perm.part.0+0x58/0xb0
[51692.242832] [  T24690]  aa_path_perm+0xef/0x150
[51692.242837] [  T24690]  apparmor_file_open+0x153/0x2e0
[51692.242840] [  T24690]  security_file_open+0x46/0xd0
[51692.242844] [  T24690]  do_dentry_open+0xe9/0x4d0
[51692.242848] [  T24690]  vfs_open+0x30/0x100

While here, initialise variables which are passed down to path_name().

Fixes: 4a134723f9 ("apparmor: move check for aa_null file to cover all cases")
Signed-off-by: Maciek Borzecki <maciek.borzecki@gmail.com>
Signed-off-by: John Johansen <john.johansen@canonical.com>
History 2026-06-13 20:20:13 -07:00
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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