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Michael Bommarito 778c2ab142 scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd()
Two latent bugs in the Text-phase handler, both present since the
original LIO integration in commit e48354ce07 ("iscsi-target: Add
iSCSI fabric support for target v4.1"):

1) DataDigest CRC buffer overread (4 bytes past text_in).

   text_in is kzalloc()'d at ALIGN(payload_length, 4).  rx_size is then
   incremented by ISCSI_CRC_LEN to make room for the received DataDigest
   in the iovec, but the same (now-bumped) rx_size is passed as the
   buffer length to iscsit_crc_buf():

       if (conn->conn_ops->DataDigest) {
               ...
               rx_size += ISCSI_CRC_LEN;
       }
       ...
       if (conn->conn_ops->DataDigest) {
               data_crc = iscsit_crc_buf(text_in, rx_size, 0, NULL);

   iscsit_crc_buf() walks rx_size bytes of text_in with crc32c(), so
   when DataDigest is negotiated it reads 4 bytes past the end of the
   text_in allocation.  KASAN reproduces this directly on the unpatched
   mainline tree as slab-out-of-bounds in crc32c() called from the Text
   PDU path.  The OOB bytes feed crc32c() and are then compared against
   the initiator-supplied checksum, so the value does not flow back to
   the attacker, but the kernel does read past the buffer on every Text
   PDU with DataDigest=CRC32C.

   Fix by passing the actual padded payload length
   (ALIGN(payload_length, 4)) that was used for the kzalloc().

2) Stale cmd->text_in_ptr re-free (double-free) on ERL>0 bad DataDigest
   drop.

   On DataDigest mismatch with ErrorRecoveryLevel > 0 the handler
   silently drops the PDU and lets the initiator plug the CmdSN gap:

               kfree(text_in);
               return 0;

   cmd->text_in_ptr still points at the freed buffer.  The next Text
   Request on the same ITT re-enters iscsit_setup_text_cmd(), which
   unconditionally does

       kfree(cmd->text_in_ptr);
       cmd->text_in_ptr = NULL;

   freeing the same pointer a second time.  Session teardown via
   iscsit_release_cmd() has the same shape and hits the same double-free
   if the connection is dropped before a second Text Request arrives.

   On an unmodified mainline tree the bug-1 CRC overread fires first on
   the initial valid Text Request and perturbs the subsequent state, so
   #4 was isolated by building a kernel with only the bug-1 hunk of this
   patch applied plus temporary printk() observability around the three
   relevant kfree() sites.  The observability prints are not part of
   this patch.  On that build, a three-PDU Text Request sequence after
   login produces two back-to-back splats:

       BUG: KASAN: double-free in iscsit_setup_text_cmd+0x??
       BUG: KASAN: double-free in iscsit_release_cmd+0x??

   showing the same pointer freed in the ERL>0 drop path and again in
   iscsit_setup_text_cmd() (next Text Request on the same ITT) and once
   more in iscsit_release_cmd() (session teardown).  On distro kernels
   with CONFIG_SLAB_FREELIST_HARDENED=y (default) the double-free
   becomes a remote kernel BUG(); on non-hardened kernels it corrupts
   the slab freelist.

   Fix by clearing cmd->text_in_ptr after the kfree() in the ERL>0 drop
   path.  With both hunks applied #4 is directly observable on the stock
   tree without observability printks; fixing bug-1 alone would mask #4
   less, not more, so the hunks are submitted together.

Both fixes are one-liners.  The Text PDU state machine is unchanged and
the wire protocol is unaffected.

Fixes: e48354ce07 ("iscsi-target: Add iSCSI fabric support for target v4.1")
Cc: stable@vger.kernel.org
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Tested-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
2026-05-22 22:24:16 -04:00
arch ARM development for 7.1-rc1 2026-04-25 07:44:26 -07:00
block block: only restrict bio allocation gfp mask asked to block 2026-04-21 11:42:12 -06:00
certs Clang build fixes for 7.1 2026-04-24 09:29:51 -07:00
crypto This push contains the following changes: 2026-04-21 08:06:43 -07:00
Documentation RTC for 7.1 2026-04-25 16:39:03 -07:00
drivers scsi: target: iscsi: Fix CRC overread and double-free in iscsit_handle_text_cmd() 2026-05-22 22:24:16 -04:00
fs ARM development for 7.1-rc1 2026-04-25 07:44:26 -07:00
include Merge branch '7.1/scsi-queue' into 7.1/scsi-fixes 2026-04-26 21:15:04 -04:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring: take page references for NOMMU pbuf_ring mmaps 2026-04-21 20:14:39 -06:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel ring-buffer fix for 7.1: 2026-04-24 15:17:23 -07:00
lib RISC-V updates for v7.1 2026-04-24 10:00:37 -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 slab fix for 7.1 2026-04-24 09:39:03 -07:00
net NFS client updates for Linux 7.1 2026-04-24 14:20:03 -07:00
rust Char/Misc/IIO/and others driver updates for 7.1-rc1 2026-04-24 13:23:50 -07:00
samples soc: drivers for 7.1 2026-04-16 20:34:34 -07:00
scripts First round of Kbuild fixes for 7.1 2026-04-25 17:04:15 -07:00
security + Cleanups 2026-04-24 09:22:21 -07:00
sound sound fixes for 7.1-rc1 2026-04-24 11:49:20 -07:00
tools Power Utilities 2026.04.25 2026-04-25 16:58:34 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt Arm: 2026-04-17 07:18:03 -07:00
.clang-format Devicetree updates for v7.0: 2026-02-11 18:27:08 -08:00
.clippy.toml rust: bump Clippy's MSRV and clean incompatible_msrv allows 2026-04-07 09:51:39 +02:00
.cocciconfig
.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 kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap Char/Misc/IIO/and others driver updates for 7.1-rc1 2026-04-24 13:23:50 -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
CREDITS Delete some obsolete networking code 2026-04-24 09:41:58 -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 Char/Misc/IIO/and others driver updates for 7.1-rc1 2026-04-24 13:23:50 -07:00
Makefile Linux 7.1-rc1 2026-04-26 14:19:00 -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