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Artem Lytkin 51e15308c6 rtnetlink: cap IFLA_VFINFO_LIST at a documented number of VFs
rtnl_fill_vf() emits one IFLA_VF_INFO per VF into the IFLA_VFINFO_LIST
nest and closes it with nla_nest_end(), which stores the accumulated
length into nla_len. That field is a u16, so a nest larger than 65535
bytes is written truncated modulo 65536. The list dates back to commit
c02db8c629 ("rtnetlink: make SR-IOV VF interface symmetric") in 2010
and has never been able to describe an arbitrary number of VFs; nothing
regressed, the encoding simply cannot represent it.

Nothing catches it on the way. if_nlmsg_size() adds rtnl_vfinfo_size()
for every VF, so the skb really is large enough and none of the nla_put()
calls fails. Userspace then walks the message with RTA_NEXT(), which
advances by the stored length, so parsing resumes inside VF payload and
the attributes after the nest are read out of VF data: IFLA_VF_PORTS,
IFLA_XDP, IFLA_LINKINFO, IFLA_PERM_ADDRESS, IFLA_AF_SPEC. iproute2
prints "!!!Deficit" and strictly validating parsers reject the message.
On CONFIG_DEBUG_NET kernels nla_nest_end() also splats, via the
DEBUG_NET_WARN_ON_ONCE() added in commit ff205bf8c5 ("netlink: add one
debug check in nla_nest_end()").

Where the wrap falls depends on what was asked for and on the host. A VF
costs 196 bytes, 296 with statistics, 236 with GUIDs and 336 with both,
and on a kernel without CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS the
statistics carry a padding attribute each and cost 32 bytes more, making
those two 328 and 368. The nest therefore overflows somewhere between 179
and 335 VFs, and ice allows 256 per PF (ICE_MAX_SRIOV_VFS), which reaches
it. Statistics are included unless the request sets
RTEXT_FILTER_SKIP_STATS, so the common case is the one that wraps first.

A limit that moves with the requested attribute set and with the host's
alignment requirements is not something userspace can be told, so use
fixed numbers instead and document them as what the interface supports:
256 VFs, or 128 when statistics are included. Both stay well inside
U16_MAX even in the largest per-VF encoding, at 60416 and 47104 bytes
respectively. rtnl_vfinfo_cap() applies the cap in both places, so
rtnl_vfinfo_size() does not size the skb for VFs that will not be
emitted.

A device with more VFs than the limit reports a shorter
IFLA_VFINFO_LIST. IFLA_NUM_VF keeps carrying the real count, and
everything after the nest stays parsable, which is the part that is
broken today. An empty nest is already emitted for a PF with no VFs, so a
list shorter than IFLA_NUM_VF is not a new encoding.

Returning -EMSGSIZE instead, which is what nla_nest_end_safe() would
give, is not an option here: a nest that does not fit in a u16 will not
fit in a retried skb either, so it would turn a link dump on such a
device into a hard failure.

The other large nests in rtnl_fill_ifinfo() were audited and cannot
overflow. IFLA_AF_SPEC is bounded by a handful of address families at
about a kilobyte each, and IFLA_VF_PORTS would need more than 560 VFs,
which no in-tree driver allows.

Reported-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://lore.kernel.org/netdev/16b289f6-b025-5dd3-443d-92d4c167e79c@intel.com/
Assisted-by: Claude:claude-fable-5
Signed-off-by: Artem Lytkin <iprintercanon@gmail.com>
Link: https://patch.msgid.link/20260801114944.115272-1-iprintercanon@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
2026-08-06 12:42:49 +02:00
arch net: tulip: remove xircom_cb driver 2026-08-05 18:33:46 -07:00
block block: fix aligning of bounced dio read bios 2026-07-16 06:11:37 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto crypto: aes - Fix conditions for selecting MAC dependencies 2026-07-09 11:06:22 -04:00
Documentation rtnetlink: cap IFLA_VFINFO_LIST at a documented number of VFs 2026-08-06 12:42:49 +02:00
drivers net: stmmac: raise TX completion interrupt at the end of an xmit burst 2026-08-05 19:09:46 -07:00
fs for-7.2-rc5-tag 2026-07-28 08:13:45 -07:00
include net/mlx5: add debugfs stats for doorbell dma pools 2026-08-05 19:02:15 -07:00
init rust: allow suspicious_runtime_symbol_definitions lint for Rust >= 1.98 2026-06-29 13:02:15 +02:00
io_uring io_uring-7.2-20260724 2026-07-24 19:58:03 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-30 12:53:19 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2026-07-30 12:53:19 -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 13 hotfixes. All are cc:stable. 11 are for MM. All are singletons - 2026-07-27 14:36:26 -07:00
net rtnetlink: cap IFLA_VFINFO_LIST at a documented number of VFs 2026-08-06 12:42:49 +02:00
rust rust: time: fix as_micros_ceil() to round correctly for negative Delta 2026-07-18 19:07:35 +02:00
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 keys: make keyring key-chunk byte order agree with keyring_diff_objects() 2026-07-23 18:23:39 +03:00
sound ALSA: hda/realtek - Add quirk for Dell Pro QC1255 2026-07-21 09:55:17 +02:00
tools selftests: drv-net: print device info at the start 2026-08-05 18:12:07 -07:00
usr kbuild: uapi: also test UAPI headers against C++ compilers 2026-03-25 13:24:42 +01:00
virt KVM/arm64 fixes for 7.2, take #2 2026-07-15 12:13:30 +02:00
.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
.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 This is again larger than usual: the backlog accumulated in the past weeks 2026-07-30 09:18:49 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
CREDITS CREDITS: Add Wolfram Sang 2026-07-14 16:34:04 +02:00
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 dinghai: add ZTE network driver support 2026-08-05 18:19:48 -07:00
Makefile Linux 7.2-rc5 2026-07-26 14:45:48 -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