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Baul Lee bc2dc66a66 vxlan: mdb: Fix use-after-free in vxlan_mdb_flush()
vxlan_mdb_flush() iterates over the MDB entries using
hlist_for_each_entry_safe(), which only tolerates the removal of the
current entry. Contrary to the comment above the loop, the removal of an
entry can trigger the removal of another entry.

Flushing the remotes of a (*, G) entry also removes the (S, G) entries
that were created for its source list, once they are left without
remotes:

vxlan_mdb_remotes_flush()
-> vxlan_mdb_remote_del()
   -> vxlan_mdb_remote_srcs_del()
      -> vxlan_mdb_remote_src_del()
         -> vxlan_mdb_remote_src_fwd_del()
            -> __vxlan_mdb_del()
               -> vxlan_mdb_entry_put()

Such an entry can be located after the (*, G) entry in the list, as
vxlan_mdb_entry_get() returns an existing entry without moving it to the
head of the list. This order is obtained by adding the (S, G) entry
before the (*, G) entry, the latter with NLM_F_REPLACE, as the addition
of the source otherwise fails with -EEXIST. The (S, G) entry is then the
entry saved by hlist_for_each_entry_safe() and it is freed while the
(*, G) entry is processed. The next iteration calls hlist_del() on it
again, writing LIST_POISON1 to LIST_POISON2 [1].

Besides device deletion, the flush is also reachable from RTM_DELMDB
with NLM_F_BULK.

Fix by re-reading the next entry after the remotes were flushed. The
current entry cannot be removed by this flush, as source lists can only
be configured on (*, G) entries and the removed entries are (S, G)
entries. It is therefore still linked and its next pointer reflects the
removals.

[1]
BUG: KASAN: wild-memory-access in vxlan_mdb_entry_put.part.0+0x328/0x588
Write of size 8 at addr dead000000000122 by task ip/327

CPU: 3 UID: 1000 PID: 327 Comm: ip Not tainted 7.2.0-rc7 #2 PREEMPT
Call trace:
 vxlan_mdb_entry_put.part.0+0x328/0x588
 vxlan_mdb_flush+0x1d8/0x25c
 vxlan_mdb_fini+0x8c/0x100
 vxlan_uninit+0x1c/0x7c
 unregister_netdevice_many_notify+0x954/0xd4c
 rtnl_dellink+0x210/0x530
 rtnetlink_rcv_msg+0x434/0x4d0
 netlink_rcv_skb+0xc4/0x204
 rtnetlink_rcv+0x18/0x24
 netlink_unicast+0x4b8/0x548
 netlink_sendmsg+0x29c/0x560
 ____sys_sendmsg+0x390/0x3ec
 ___sys_sendmsg+0x114/0x188
 __sys_sendmsg+0xf0/0x178
 __arm64_sys_sendmsg+0x48/0x60
 invoke_syscall.constprop.0+0x58/0x180
 el0_svc_common.constprop.0+0x74/0x140
 do_el0_svc+0x30/0x40
 el0_svc+0x38/0x98
 el0t_64_sync_handler+0xa0/0xe4
 el0t_64_sync+0x198/0x19c

Fixes: a3a48de5ea ("vxlan: mdb: Add MDB control path support")
Signed-off-by: Baul Lee <baul.lee@xbow.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260814153547.29567-1-baul.lee@xbow.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
History 2026-08-18 11:58:02 +02:00
arch m68k fixes for v7.2 2026-08-13 07:00:26 -07:00
block block: stop the timeout timer when releasing a never added disk 2026-07-29 05:23:20 -06:00
certs treewide: fix indentation and whitespace in Kconfig files 2026-05-28 21:24:42 -07:00
crypto This push contains the following changes: 2026-08-10 08:36:22 -07:00
Documentation USB / Thunderbolt fixes for 7.2-rc7 2026-08-08 16:33:04 -07:00
drivers vxlan: mdb: Fix use-after-free in vxlan_mdb_flush() 2026-08-18 11:58:02 +02:00
fs tracing fixes for 7.2: 2026-08-09 08:47:31 -07:00
include There is a known WiFi/mt76 regression, waiting for a complete fix that 2026-08-13 08:37:26 -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: preserve task restrictions across exec 2026-07-30 14:40:22 -06:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel tracing fixes for 7.2: 2026-08-09 08:47:31 -07:00
lib This push contains the following changes: 2026-08-10 08:36:22 -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 17 hotfixes. 15 are cc:stable. 16 are for MM. 2026-08-06 20:29:38 -07:00
net mpls: reload header after pskb_may_pull() 2026-08-18 10:51:37 +02:00
rust Driver core fixes for 7.2-rc7 2026-08-08 07:13:29 -07:00
samples samples/damon/mtier: error out for zero quota goal target values 2026-08-04 20:02:02 -07:00
scripts kbuild: rpm-pkg: Preserve BTF sections in kernel modules during debuginfo stripping 2026-07-29 16:21:42 -07:00
security selinux/stable-7.2 PR 20260805 2026-08-05 13:40:11 -07:00
sound ALSA: usb-audio: Fix sticky mixer regressions on M-Audio Fast Track Ultra 2026-08-07 10:35:31 +02:00
tools There is a known WiFi/mt76 regression, waiting for a complete fix that 2026-08-13 08:37:26 -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 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 There is a known WiFi/mt76 regression, waiting for a complete fix that 2026-08-13 08:37:26 -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 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 Char / Misc and documentation fixes for 7.2-rc7 2026-08-08 16:25:59 -07:00
Makefile Linux 7.2-rc7 2026-08-09 14:54:50 -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