Xingui Yang 8ddc0c2691 scsi: hisi_sas: Fix NULL pointer exception during user_scan()
user_scan() invokes updated sas_user_scan() for channel 0, and if
successful, iteratively scans remaining channels (1 to shost->max_channel)
via scsi_scan_host_selected() in commit 37c4e72b06 ("scsi: Fix
sas_user_scan() to handle wildcard and multi-channel scans"). However,
hisi_sas supports only one channel, and the current value of max_channel is
1. sas_user_scan() for channel 1 will trigger the following NULL pointer
exception:

[  441.554662] Unable to handle kernel NULL pointer dereference at virtual address 00000000000008b0
[  441.554699] Mem abort info:
[  441.554710]   ESR = 0x0000000096000004
[  441.554718]   EC = 0x25: DABT (current EL), IL = 32 bits
[  441.554723]   SET = 0, FnV = 0
[  441.554726]   EA = 0, S1PTW = 0
[  441.554730]   FSC = 0x04: level 0 translation fault
[  441.554735] Data abort info:
[  441.554737]   ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
[  441.554742]   CM = 0, WnR = 0, TnD = 0, TagAccess = 0
[  441.554747]   GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
[  441.554752] user pgtable: 4k pages, 48-bit VAs, pgdp=00000828377a6000
[  441.554757] [00000000000008b0] pgd=0000000000000000, p4d=0000000000000000
[  441.554769] Internal error: Oops: 0000000096000004 [#1]  SMP
[  441.629589] Modules linked in: arm_spe_pmu arm_smmuv3_pmu tpm_tis_spi hisi_uncore_sllc_pmu hisi_uncore_pa_pmu hisi_uncore_l3c_pmu hisi_uncore_hha_pmu hisi_uncore_ddrc_pmu hisi_uncore_cpa_pmu hns3_pmu hisi_ptt hisi_pcie_pmu tpm_tis_core spidev spi_hisi_sfc_v3xx hisi_uncore_pmu spi_dw_mmio fuse hclge hclge_common hisi_sec2 hisi_hpre hisi_zip hisi_qm hns3 hisi_sas_v3_hw sm3_ce sbsa_gwdt hnae3 hisi_sas_main uacce hisi_dma i2c_hisi dm_mirror dm_region_hash dm_log dm_mod
[  441.670819] CPU: 46 UID: 0 PID: 6994 Comm: bash Kdump: loaded Not tainted 7.0.0-rc2+ #84 PREEMPT
[  441.691327] pstate: 81400009 (Nzcv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[  441.698277] pc : sas_find_dev_by_rphy+0x44/0x118
[  441.702896] lr : sas_find_dev_by_rphy+0x3c/0x118
[  441.707502] sp : ffff80009abbba40
[  441.710805] x29: ffff80009abbba40 x28: ffff082819a40008 x27: ffff082810c37c08
[  441.717930] x26: ffff082810c37c28 x25: ffff082819a40290 x24: ffff082810c37c00
[  441.725054] x23: 0000000000000000 x22: 0000000000000001 x21: ffff082819a40000
[  441.732179] x20: ffff082819a40290 x19: 0000000000000000 x18: 0000000000000020
[  441.739304] x17: 0000000000000000 x16: ffffb5dad6bda690 x15: 00000000ffffffff
[  441.746428] x14: ffff082814c3b26c x13: 00000000ffffffff x12: ffff082814c3b26a
[  441.753553] x11: 00000000000000c0 x10: 000000000000003a x9 : ffffb5dad5ea94f4
[  441.760678] x8 : 000000000000003a x7 : ffff80009abbbab0 x6 : 0000000000000030
[  441.767802] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[  441.774926] x2 : ffff08280f35a300 x1 : ffffb5dad7127180 x0 : 0000000000000000
[  441.782053] Call trace:
[  441.784488]  sas_find_dev_by_rphy+0x44/0x118 (P)
[  441.789095]  sas_target_alloc+0x24/0xb0
[  441.792920]  scsi_alloc_target+0x290/0x330
[  441.797010]  __scsi_scan_target+0x88/0x258
[  441.801096]  scsi_scan_channel+0x74/0xb8
[  441.805008]  scsi_scan_host_selected+0x170/0x188
[  441.809615]  sas_user_scan+0xfc/0x148
[  441.813267]  store_scan+0x10c/0x180
[  441.816743]  dev_attr_store+0x20/0x40
[  441.820398]  sysfs_kf_write+0x84/0xa8
[  441.824054]  kernfs_fop_write_iter+0x130/0x1c8
[  441.828487]  vfs_write+0x2c0/0x370
[  441.831880]  ksys_write+0x74/0x118
[  441.835271]  __arm64_sys_write+0x24/0x38
[  441.839182]  invoke_syscall+0x50/0x120
[  441.842919]  el0_svc_common.constprop.0+0xc8/0xf0
[  441.847611]  do_el0_svc+0x24/0x38
[  441.850913]  el0_svc+0x38/0x158
[  441.854043]  el0t_64_sync_handler+0xa0/0xe8
[  441.858214]  el0t_64_sync+0x1ac/0x1b0
[  441.861865] Code: aa1303e0 97ff70a8 34ffff80 d10a4273 (f9445a75)
[  441.867946] ---[ end trace 0000000000000000 ]---

Therefore, set max_channel to 0.

Fixes: e21fe3a526 ("scsi: hisi_sas: add initialisation for v3 pci-based controller")
Signed-off-by: Xingui Yang <yangxingui@huawei.com>
Signed-off-by: Yihang Li <liyihang9@huawei.com>
Link: https://patch.msgid.link/20260305064039.4096775-1-liyihang9@huawei.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2026-03-07 11:16:34 -05:00
2026-01-26 19:07:09 -08:00
2022-09-28 09:02:20 +02:00
2025-02-19 14:53:27 -07:00
2026-02-22 13:18:59 -08:00

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
Description
No description provided
Readme 3.7 GiB
Languages
C 97.1%
Assembly 1%
Shell 0.6%
Rust 0.4%
Python 0.4%
Other 0.3%