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Ritesh Harjani (IBM) 51d8c78be0 mm/kasan: fix double free for kasan pXds
kasan_free_pxd() assumes the page table is always struct page aligned. 
But that's not always the case for all architectures.  E.g.  In case of
powerpc with 64K pagesize, PUD table (of size 4096) comes from slab cache
named pgtable-2^9.  Hence instead of page_to_virt(pxd_page()) let's just
directly pass the start of the pxd table which is passed as the 1st
argument.

This fixes the below double free kasan issue seen with PMEM:

radix-mmu: Mapped 0x0000047d10000000-0x0000047f90000000 with 2.00 MiB pages
==================================================================
BUG: KASAN: double-free in kasan_remove_zero_shadow+0x9c4/0xa20
Free of addr c0000003c38e0000 by task ndctl/2164

CPU: 34 UID: 0 PID: 2164 Comm: ndctl Not tainted 6.19.0-rc1-00048-gea1013c15392 #157 VOLUNTARY
Hardware name: IBM,9080-HEX POWER10 (architected) 0x800200 0xf000006 of:IBM,FW1060.00 (NH1060_012) hv:phyp pSeries
Call Trace:
 dump_stack_lvl+0x88/0xc4 (unreliable)
 print_report+0x214/0x63c
 kasan_report_invalid_free+0xe4/0x110
 check_slab_allocation+0x100/0x150
 kmem_cache_free+0x128/0x6e0
 kasan_remove_zero_shadow+0x9c4/0xa20
 memunmap_pages+0x2b8/0x5c0
 devm_action_release+0x54/0x70
 release_nodes+0xc8/0x1a0
 devres_release_all+0xe0/0x140
 device_unbind_cleanup+0x30/0x120
 device_release_driver_internal+0x3e4/0x450
 unbind_store+0xfc/0x110
 drv_attr_store+0x78/0xb0
 sysfs_kf_write+0x114/0x140
 kernfs_fop_write_iter+0x264/0x3f0
 vfs_write+0x3bc/0x7d0
 ksys_write+0xa4/0x190
 system_call_exception+0x190/0x480
 system_call_vectored_common+0x15c/0x2ec
---- interrupt: 3000 at 0x7fff93b3d3f4
NIP:  00007fff93b3d3f4 LR: 00007fff93b3d3f4 CTR: 0000000000000000
REGS: c0000003f1b07e80 TRAP: 3000   Not tainted  (6.19.0-rc1-00048-gea1013c15392)
MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 48888208  XER: 00000000
<...>
NIP [00007fff93b3d3f4] 0x7fff93b3d3f4
LR [00007fff93b3d3f4] 0x7fff93b3d3f4
---- interrupt: 3000

 The buggy address belongs to the object at c0000003c38e0000
  which belongs to the cache pgtable-2^9 of size 4096
 The buggy address is located 0 bytes inside of
  4096-byte region [c0000003c38e0000, c0000003c38e1000)

 The buggy address belongs to the physical page:
 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3c38c
 head: order:2 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
 memcg:c0000003bfd63e01
 flags: 0x63ffff800000040(head|node=6|zone=0|lastcpupid=0x7ffff)
 page_type: f5(slab)
 raw: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000
 raw: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01
 head: 063ffff800000040 c000000140058980 5deadbeef0000122 0000000000000000
 head: 0000000000000000 0000000080200020 00000000f5000000 c0000003bfd63e01
 head: 063ffff800000002 c00c000000f0e301 00000000ffffffff 00000000ffffffff
 head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000004
 page dumped because: kasan: bad access detected

[  138.953636] [   T2164] Memory state around the buggy address:
[  138.953643] [   T2164]  c0000003c38dff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  138.953652] [   T2164]  c0000003c38dff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  138.953661] [   T2164] >c0000003c38e0000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  138.953669] [   T2164]                    ^
[  138.953675] [   T2164]  c0000003c38e0080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  138.953684] [   T2164]  c0000003c38e0100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
[  138.953692] [   T2164] ==================================================================
[  138.953701] [   T2164] Disabling lock debugging due to kernel taint

Link: https://lkml.kernel.org/r/2f9135c7866c6e0d06e960993b8a5674a9ebc7ec.1771938394.git.ritesh.list@gmail.com
Fixes: 0207df4fa1 ("kernel/memremap, kasan: make ZONE_DEVICE with work with KASAN")
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Ritesh Harjani (IBM)" <ritesh.list@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
History 2026-04-05 13:53:11 -07:00
arch x86/vdso: undefine CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP for vdso32 2026-04-05 13:53:09 -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 hugetlb: update vmemmap_dedup.rst 2026-04-05 13:53:10 -07:00
drivers zram: use statically allocated compression algorithm names 2026-04-05 13:53:07 -07:00
fs folio_batch: rename PAGEVEC_SIZE to FOLIO_BATCH_SIZE 2026-04-05 13:53:07 -07:00
include mm: replace READ_ONCE() in pud_trans_unstable() 2026-04-05 13:53:11 -07:00
init io_uring-7.0-20260305 2026-03-06 08:31:36 -08:00
io_uring io_uring-7.0-20260320 2026-03-20 09:58:56 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel mm: rename the 'compound_head' field in the 'struct page' to 'compound_info' 2026-04-05 13:53:08 -07:00
lib maple_tree: clean up mas_wr_node_store() 2026-04-05 13:52:57 -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/kasan: fix double free for kasan pXds 2026-04-05 13:53:11 -07:00
net Including fixes from wireless, Bluetooth and netfilter. 2026-03-19 11:25:40 -07:00
rust Rust fixes for v7.0 (2nd) 2026-03-14 12:35:16 -07:00
samples drm-fixes for 7.0-rc4 2026-03-13 15:38:55 -07:00
scripts livepatch/klp-build: Fix inconsistent kernel version 2026-03-16 12:50:17 -07:00
security xen/privcmd: add boot control for restricted usage in domU 2026-03-20 12:06:01 +01:00
sound driver core: platform: use generic driver_override infrastructure 2026-03-17 20:30:57 +01:00
tools kho: remove finalize state and clients 2026-04-05 13:53:04 -07:00
usr kbuild: uapi: drop dependency on CC_CAN_LINK 2026-01-16 15:02:11 -07:00
virt KVM generic changes for 7.0 2026-03-11 18:01:55 +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 mailmap: update email address for Muhammad Usama Anjum 2026-03-23 09:35:05 -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 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 folio_batch: rename pagevec.h to folio_batch.h 2026-04-05 13:53:07 -07:00
Makefile Linux 7.0-rc5 2026-03-22 14:42:17 -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