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Yehyeong Lee 464f5afa92 IB/isert: delay the final Login Response until the session is registered
isert_put_login_tx() puts the final Login Response on the wire before
__transport_register_session(), which iscsi_post_login_handler() reaches
only after iscsi_target_do_login() returns.  An initiator that issues a
SCSI command as soon as it sees that response can have it executed against
an se_session whose se_tpg is still NULL, and the ib-comp-wq worker oopses
on the NULL dereference.

 Oops: general protection fault, probably for non-canonical address 0xdffffc000000000f: 0000 [#1] SMP KASAN NOPTI
 KASAN: null-ptr-deref in range [0x0000000000000078-0x000000000000007f]
 CPU: 0 UID: 0 PID: 178 Comm: kworker/0:1H Not tainted 7.2.0-rc5-V2CTL-gf5098b6bae76 #10 PREEMPT(lazy)
 Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
 Workqueue: ib-comp-wq ib_cq_poll_work
 RIP: 0010:target_submit+0xbe/0x390
 Code: fa 48 c1 ea 03 80 3c 02 00 0f 85 89 02 00 00 48 b8 00 00 00 00 00 fc ff df 4d 8b 64 24 18 49 8d 7c 24 78 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 5a 02 00 00 48 8d 7b 78 4d 8b 6c 24 78 48 b8 00
 RSP: 0018:ffff8881058cfa78 EFLAGS: 00010206
 RAX: dffffc0000000000 RBX: ffff88810c78c6f0 RCX: ffffffff964bb363
 RDX: 000000000000000f RSI: 00000000fffffe00 RDI: 0000000000000078
 RBP: 1ffff11020b19f52 R08: 0000000000000001 R09: ffffed1020b19f52
 R10: 0000000000000003 R11: ffff88810596c000 R12: 0000000000000000
 R13: ffff88810c61b000 R14: ffff88810c6a3400 R15: ffff88810c61b044
 FS:  0000000000000000(0000) GS:ffff8881822b2000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007f1f1b83c000 CR3: 000000006fe72001 CR4: 0000000000770ef0
 PKRU: 55555554
 Call Trace:
  <TASK>
  ? __pfx__raw_spin_lock_bh+0x10/0x10
  ? __pfx_target_submit+0x10/0x10
  ? mutex_lock+0x81/0xe0
  ? __pfx_mutex_lock+0x10/0x10
  ? iscsit_execute_cmd+0x650/0x850
  iscsit_sequence_cmd+0x186/0x3d0
  iscsit_process_scsi_cmd+0x87/0x300
  isert_recv_done+0x1002/0x2390
  ? __pfx_isert_recv_done+0x10/0x10
  ? rxe_poll_cq+0x253/0x3d0
  ? finish_task_switch.isra.0+0x1dc/0xa70
  __ib_process_cq+0xe1/0x390
  ib_cq_poll_work+0x46/0x150
  process_one_work+0x633/0x1030
  ? assign_work+0x11d/0x370
  worker_thread+0x45b/0xd10
  ? __pfx_worker_thread+0x10/0x10
  ? __pfx_worker_thread+0x10/0x10
  kthread+0x2c6/0x3b0
  ? recalc_sigpending+0x15c/0x1e0
  ? __pfx_kthread+0x10/0x10
  ret_from_fork+0x36e/0x5a0
  ? __pfx_ret_from_fork+0x10/0x10
  ? __switch_to+0x572/0xdd0
  ? __pfx_kthread+0x10/0x10
  ret_from_fork_asm+0x1a/0x30
  </TASK>
 Modules linked in:
 ---[ end trace 0000000000000000 ]---

Delay the final Login Response instead.  isert_get_rx_pdu() runs from
iscsi_target_rx_thread() after conn->rx_login_comp, completed by
iscsi_post_login_handler() after __transport_register_session(); iscsi-TCP
and cxgbit already take PDUs from that thread, isert alone does not.  The
buffers are still posted first, so the initiator's first command does not
meet an empty receive queue and nothing depends on RNR flow control, and
the header and payload live in isert_conn, not in the struct iscsi_login
that iscsi_target_nego_release() frees first.

Over rxe, 400 login cycles per run, the oops appeared in 10 of 20
unpatched runs and in none of 20 runs with this patch.  An
initiator that never waits is handled by the next patch.

Not tested: iWARP, discovery sessions over iSER, and real HCAs.

Fixes: b8d26b3be8 ("iser-target: Add iSCSI Extensions for RDMA (iSER) target driver")
Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
Link: https://patch.msgid.link/20260731041212.1733364-1-yhlee@isslab.korea.ac.kr
Signed-off-by: Leon Romanovsky <leon@kernel.org>
History 2026-08-06 06:23:30 -04:00
arch s390 updates for 7.2-rc3 2026-07-12 11:38:00 -07:00
block block: remove redundant GD_NEED_PART_SCAN in add_disk_final() 2026-07-10 09:08:50 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
Documentation mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
drivers IB/isert: delay the final Login Response until the session is registered 2026-08-06 06:23:30 -04:00
fs mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
include RDMA/mana_ib: UC QP support for UAPI 2026-08-05 10:44:30 -04:00
init mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
io_uring io_uring-7.2-20260710 2026-07-11 09:24:38 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
lib tracing: Prevent out-of-bounds read in glob matching 2026-07-07 10:42:28 -04:00
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: do file ownership checks with the proper mount idmap 2026-07-01 19:02:56 -07:00
net mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
rust Rust changes for v7.2 (addendum) 2026-06-24 15:11:08 -07:00
samples tracing fixes for 7.2: 2026-07-12 09:46:37 -07:00
scripts scripts/sorttable: Handle RISC-V patchable ftrace entries 2026-06-25 13:15:03 -06:00
security selinux/stable-7.2 PR 20260710 2026-07-10 18:59:29 -07:00
sound sound fixes for 7.2-rc2 2026-07-05 05:26:45 -10:00
tools mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt s390: 2026-06-25 10:21:13 -07:00
.clang-format clang-format: fix formatting of guard() and scoped_guard() statements 2026-05-28 21:24:41 -07:00
.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 myself 2026-04-02 16:48:25 +02:00
.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 20 hotfixes. 17 are for MM. 12 are cc:stable and the remaining 8 2026-07-06 18:51:36 -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 mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -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 USB fixes for 7.2-rc3 2026-07-12 12:12:41 -07:00
Makefile Linux 7.2-rc3 2026-07-12 14:16:39 -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