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Srinivasan Shanmugam 809773e066 drm/amdgpu: Avoid NULL dereference in discovery topology coredump path v3
When a GPU fault or timeout happens, the driver creates a devcoredump
to collect debug information.

During this, amdgpu_devcoredump_format() calls
amdgpu_discovery_dump() to print IP discovery data.

amdgpu_discovery_dump() uses:
  adev->discovery.ip_top

and then accesses:
  ip_top->die_kset

amdgpu_discovery_dump() uses adev->discovery.ip_top. However,
ip_top may be NULL if the discovery topology was never initialized.

The current code does not check for this before using ip_top. As a
result, when ip_top is NULL, the coredump worker crashes while taking
the spinlock for ip_top->die_kset.

Fix this by checking for a missing ip_top before walking the discovery
topology. If it is unavailable, print a short message in the dump and
return safely.

- If ip_top is NULL, print a message and skip the dump
- Also add the same check in the cleanup path

This makes the coredump and cleanup paths safe even when the
discovery topology is not available.

KASAN trace:
[  522.228252] [IGT] amd_deadlock: starting subtest amdgpu-deadlock-sdma
[  522.240681] [IGT] amd_deadlock: starting dynamic subtest amdgpu-deadlock-sdma

...

[  522.952317] Write of size 4 at addr 0000000000000050 by task kworker/u129:5/5434
[  522.937526] BUG: KASAN: null-ptr-deref in _raw_spin_lock+0x66/0xc0
[  522.967659] Workqueue: events_unbound amdgpu_devcoredump_deferred_work [amdgpu]

...

[  522.969445] Call Trace:
[  522.969508]  _raw_spin_lock+0x66/0xc0
[  522.969518]  ? __pfx__raw_spin_lock+0x10/0x10
[  522.969534]  amdgpu_discovery_dump+0x61/0x530 [amdgpu]
[  522.971346]  ? pick_next_task_fair+0x3f6/0x1c60
[  522.971363]  amdgpu_devcoredump_format+0x84f/0x26f0 [amdgpu]
[  522.973188]  ? __pfx_amdgpu_devcoredump_format+0x10/0x10 [amdgpu]
[  522.975012]  ? psi_task_switch+0x2b5/0x9b0
[  522.975027]  ? __pfx___drm_printfn_coredump+0x10/0x10 [drm]
[  522.975198]  ? __pfx___drm_puts_coredump+0x10/0x10 [drm]
[  522.975366]  ? __schedule+0x113c/0x38d0
[  522.975381]  amdgpu_devcoredump_deferred_work+0x4c/0x1f0 [amdgpu]

v2: Updated commit message - Clarified that ip_top is not freed, it can
    just be NULL if discovery was not initialized. (Christian/Lijo)

v3: Removed the extra drm_warn() for sysfs init failure as sysfs already
    reports errors. (Christian)

Fixes: e81eff80aa ("drm/amdgpu: include ip discovery data in devcoredump")
Cc: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Srinivasan Shanmugam <srinivasan.shanmugam@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
History 2026-03-23 14:04:43 -04:00
arch EFI fixes for v7.0 #2 2026-03-08 12:13:09 -07:00
block block-7.0-20260305 2026-03-06 08:36:18 -08:00
certs Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
crypto crypto: testmgr - Fix stale references to aes-generic 2026-03-03 11:57:15 -08:00
Documentation Merge tag 'drm-xe-next-2026-03-12' of https://gitlab.freedesktop.org/drm/xe/kernel into drm-next 2026-03-16 12:21:08 +10:00
drivers drm/amdgpu: Avoid NULL dereference in discovery topology coredump path v3 2026-03-23 14:04:43 -04:00
fs eight client fixes 2026-03-06 16:07:22 -08:00
include Merge tag 'drm-intel-next-2026-03-16' of https://gitlab.freedesktop.org/drm/i915/kernel into drm-next 2026-03-17 15:44:26 +10:00
init io_uring-7.0-20260305 2026-03-06 08:31:36 -08:00
io_uring io_uring-7.0-20260305 2026-03-06 08:31:36 -08:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Make clock_adjtime() syscall timex validation slightly more 2026-03-07 17:09:15 -08:00
lib linux_kselftest-kunit-fixes-7.0-rc3 2026-03-06 12:34:49 -08:00
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 Merge drm/drm-next into drm-xe-next 2026-03-12 07:23:23 -07:00
net xdp: produce a warning when calculated tailroom is negative 2026-03-05 08:02:05 -08:00
rust linux_kselftest-kunit-fixes-7.0-rc3 2026-03-06 12:34:49 -08:00
samples USB / Thunderbolt changes for 7.0-rc1 2026-02-17 09:36:43 -08:00
scripts kbuild: install-extmod-build: Package resolve_btfids if necessary 2026-02-26 14:49:34 -07:00
security Convert remaining multi-line kmalloc_obj/flex GFP_KERNEL uses 2026-02-22 08:26:33 -08:00
sound ASoC: Fixes for v7.0 2026-03-05 17:22:14 +01:00
tools bpf-fixes 2026-03-07 12:20:37 -08:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM: always define KVM_CAP_SYNC_MMU 2026-02-28 15:31:35 +01:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: clean Rust 1.88.0's warning about clippy::disallowed_macros configuration 2025-05-07 00:11:47 +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 MAINTAINERS: remove Alyssa Rosenzweig 2025-09-18 21:17:31 +02:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore rust: kbuild: add proc macro library support 2025-11-24 17:15:36 +01:00
.mailmap linux_kselftest-kunit-fixes-7.0-rc3 2026-03-06 12:34:49 -08:00
.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 MAINTAINERS: remove Thomas Falcon from IBM ibmvnic 2026-03-05 07:35:45 -08:00
Kbuild sched: Make migrate_{en,dis}able() inline 2025-09-25 09:57:16 +02:00
Kconfig io_uring: Rename KConfig to Kconfig 2025-02-19 14:53:27 -07:00
MAINTAINERS Merge drm/drm-next into drm-misc-next 2026-03-12 08:25:41 +01:00
Makefile Linux 7.0-rc3 2026-03-08 16:56:54 -07:00
README docs: add AI Coding Assistants documentation 2026-01-06 14:55:06 -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
* 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