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Yehyeong Lee 2488b5b482 IB/isert: reject login PDUs declaring more data than was received
isert_login_recv_done() records how many bytes the HCA actually placed in
the login buffer, but nothing compares that against the length the login
PDU's BHS declares.  isert_rx_login_req() copies min(login_req_len,
MAX_KEY_VALUE_PAIRS) bytes into login->req_buf, and the login code then
reads the declared length back out of that buffer - for the first PDU in
iscsi_target_locate_portal(),

	payload_length = ntoh24(login_req->dlength);
	tmpbuf = kmemdup_nul(login->req_buf, payload_length, GFP_KERNEL);

and for the ones after it in iscsi_decode_text_input(), reached from
iscsi_target_do_login().

login->req_buf is a fixed MAX_KEY_VALUE_PAIRS (8192) byte allocation, so
an initiator that declares more than it sends reads off the end of it,
before authentication and with the length under its control:

  BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43/0x80
  Read of size 8193 at addr ffff8881056a8000 by task iscsi_np/167
   __asan_memcpy+0x23/0x60
   kmemdup_nul+0x43/0x80
   iscsi_target_locate_portal+0x48d/0x1180
   iscsi_target_login_thread+0x19a9/0x3350
  Allocated by task 167:
   __kmalloc_cache_noprof+0x158/0x370
   iscsi_target_login_thread+0x971/0x3350
  which belongs to the cache kmalloc-8k of size 8192
  allocated 8192-byte region

Falsifying the second login PDU instead reaches the other reader, on the
same buffer:

  BUG: KASAN: slab-out-of-bounds in kmemdup_nul+0x43/0x80
  Read of size 8193 at addr ffff888104d10000 by task kworker/1:1/50
  Workqueue: isert_login_wq iscsi_target_do_login_rx
   __asan_memcpy+0x23/0x60
   kmemdup_nul+0x43/0x80
   iscsi_decode_text_input+0xc6/0x11c0
   iscsi_target_do_login+0x261/0x1470
   iscsi_target_do_login_rx+0x51d/0x7d0

iscsit over TCP is not exposed: iscsit_get_login_rx() validates the
declared length with iscsi_target_check_login_request() and then reads
exactly that many bytes off the socket, so the declared length governs
how much arrives rather than how much is copied out of an already-filled
buffer.  isert does not call iscsi_target_check_login_request() at all.

Reject a login PDU whose declared DataSegmentLength exceeds what was
received, in both paths that reach isert_rx_login_req():
isert_get_login_rx() for the first login PDU and isert_login_recv_done()
for the ones after it.  dlength <= login_req_len is allowed because the
received count can include up to three bytes of iSCSI padding.

Once the check is in place the copy out can no longer exceed the copy in:
the posted login SGE is ISER_RX_PAYLOAD_SIZE, so login_req_len cannot
exceed MAX_KEY_VALUE_PAIRS and the min() in isert_rx_login_req() is
login_req_len.

Like the existing short-PDU check added by 29e7b925ae, the reject in
isert_login_recv_done() returns without completing login_req_comp, so a
malformed subsequent PDU leaves the login to be torn down by the login
timer rather than failing immediately.  The first-PDU path returns an
error and fails straight away.

Reproduced on 7.2.0-rc4 with soft-RoCE (rdma_rxe) under KASAN, using an
initiator that sends the real key=value payload while declaring 8193 in
the BHS, on the first login PDU and on the second in separate runs.  The
reported read size tracks the declared value exactly; 16384 and 61440
behave the same.  Unpatched 3 of 3 runs report on each of the two paths,
patched 0 of 3 on both, run alternately in a single session, and a normal
login still completes on the patched build.

Fixes: b8d26b3be8 ("iser-target: Add iSCSI Extensions for RDMA (iSER) target driver")
Suggested-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Yehyeong Lee <yhlee@isslab.korea.ac.kr>
Link: https://patch.msgid.link/20260726163931.971063-3-yhlee@isslab.korea.ac.kr
Signed-off-by: Leon Romanovsky <leon@kernel.org>
History 2026-07-29 09:07:06 -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: reject login PDUs declaring more data than was received 2026-07-29 09:07:06 -04:00
fs mlx5: Deprecate latency-sensitive QPs feature 2026-07-27 02:37:29 -04:00
include RDMA/bnxt_re: Add uverbs object handle path for CQ/SRQ toggle page 2026-07-28 08:03:10 -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