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Antony Antony ea528f1823 xfrm: reject optional IPTFS templates in outbound policies
syzbot reported a stack-out-of-bounds read in xfrm_state_find()
which flows from xfrm_tmpl_resolve_one().

Commit 3d776e31c8 ("xfrm: Reject optional tunnel/BEET mode
templates in outbound policies") disallowed optional tunnel and
BEET in outbound policies to prevent this. Later when IPTFS
added, it was not covered by that fix and can still trigger
the out-of-bounds read;

Extend the check to disallow optional IPTFS in outbound policies
as well. IPTFS should be identical to tunnel mode.
IN and FWD policies are not affected: xfrm_tmpl_resolve_one()
is only reachable via the outbound path.

Reproducer, before:

ip link add dummy0 type dummy
ip link set dummy0 up
ip addr add 10.1.1.1/24 dev dummy0
ip xfrm policy add src 10.1.1.1/32 dst 10.1.1.2/32 dir out tmpl
  src fc00::dead:1 dst fc00::dead:2 proto esp reqid 1 mode iptfs
  level use tmpl src fc00::dead:1 dst fc00::dead:2 proto esp reqid
  2 mode transport
ping -W 1 -c 1 10.1.1.2
PING 10.1.1.2 (10.1.1.2) 56(84) bytes of data.

[   64.168420] ==================================================================
[   64.169977] BUG: KASAN: stack-out-of-bounds in __xfrm6_addr_hash+0x11e/0x170
[   64.169977] Read of size 4 at addr ffff88800e1ffd20 by task ping/2844

[   64.169977] CPU: 2 UID: 0 PID: 2844 Comm: ping Not tainted 7.1.0-rc7-00180-geb23b588430a #98 PREEMPT(full)
[   64.169977] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
[   64.169977] Call Trace:
[   64.169977]  <TASK>
[   64.169977]  dump_stack_lvl+0x47/0x70
[   64.169977]  ? __xfrm6_addr_hash+0x11e/0x170
[   64.169977]  print_report+0x152/0x4b0
[   64.169977]  ? ksys_mmap_pgoff+0x6d/0xa0
[   64.169977]  ? entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   64.169977]  ? rcu_read_unlock_sched+0xa/0x20
[   64.169977]  ? __virt_addr_valid+0x21b/0x230
[   64.169977]  ? __xfrm6_addr_hash+0x11e/0x170
[   64.169977]  kasan_report+0xa8/0xd0
[   64.169977]  ? __xfrm6_addr_hash+0x11e/0x170
[   64.169977]  __xfrm6_addr_hash+0x11e/0x170
[   64.169977]  __xfrm_dst_hash+0x24/0xc0
[   64.169977]  xfrm_state_find+0xa2d/0x2f90
[   64.169977]  ? __pfx_xfrm_state_find+0x10/0x10
[   64.169977]  ? __pfx_ftrace_graph_ret_addr+0x10/0x10
[   64.169977]  ? __pfx_ftrace_graph_ret_addr+0x10/0x10
[   64.169977]  xfrm_tmpl_resolve_one+0x210/0x570
[   64.169977]  ? __pfx_xfrm_tmpl_resolve_one+0x10/0x10
[   64.169977]  ? __pfx_stack_trace_consume_entry+0x10/0x10
[   64.169977]  ? kernel_text_address+0x5b/0x80
[   64.169977]  ? __kernel_text_address+0xe/0x30
[   64.169977]  ? unwind_get_return_address+0x5e/0x90
[   64.169977]  ? arch_stack_walk+0x8c/0xe0
[   64.169977]  xfrm_tmpl_resolve+0x130/0x200
[   64.169977]  ? __pfx_xfrm_tmpl_resolve+0x10/0x10
[   64.169977]  ? __pfx_xfrm_policy_inexact_lookup_rcu+0x10/0x10
[   64.169977]  ? __refcount_add_not_zero.constprop.0+0xb2/0x110
[   64.169977]  ? __pfx___refcount_add_not_zero.constprop.0+0x10/0x10
[   64.169977]  xfrm_resolve_and_create_bundle+0xd5/0x310
[   64.169977]  ? __pfx_xfrm_resolve_and_create_bundle+0x10/0x10
[   64.169977]  ? __pfx_xfrm_policy_lookup_bytype+0x10/0x10
[   64.169977]  ? __pfx_xfrm_policy_lookup_bytype+0x10/0x10
[   64.169977]  xfrm_lookup_with_ifid+0x3d8/0xb80
[   64.169977]  ? __pfx_xfrm_lookup_with_ifid+0x10/0x10
[   64.169977]  ? ip_route_output_key_hash+0xc6/0x110
[   64.169977]  ? kasan_save_track+0x10/0x30
[   64.169977]  xfrm_lookup_route+0x18/0xe0
[   64.169977]  ip4_datagram_release_cb+0x4c9/0x530
[   64.169977]  ? __pfx_ip4_datagram_release_cb+0x10/0x10
[   64.169977]  ? do_raw_spin_lock+0x71/0xc0
[   64.169977]  ? __pfx_do_raw_spin_lock+0x10/0x10
[   64.169977]  release_sock+0xb0/0x170
[   64.169977]  udp_connect+0x43/0x50
[   64.169977]  __sys_connect+0xa6/0x100
[   64.169977]  ? alloc_fd+0x2e9/0x300
[   64.169977]  ? __pfx___sys_connect+0x10/0x10
[   64.169977]  ? preempt_latency_start+0x1f/0x70
[   64.169977]  ? fd_install+0x7e/0x150
[   64.169977]  ? rcu_read_unlock_sched+0xa/0x20
[   64.169977]  ? __sys_socket+0xdf/0x130
[   64.169977]  ? __pfx___sys_socket+0x10/0x10
[   64.169977]  ? vma_refcount_put+0x43/0xa0
[   64.169977]  __x64_sys_connect+0x7e/0x90
[   64.169977]  do_syscall_64+0x11b/0x2b0
[   64.169977]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   64.169977] RIP: 0033:0x7f4851ecb570
[   64.169977] Code: 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 80 3d f9 ca 0d 00 00 74 17 b8 2a 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 58 c3 0f 1f 80 00 00 00 00 48 83 ec 18 89 54
[   64.169977] RSP: 002b:00007ffc830e3498 EFLAGS: 00000202 ORIG_RAX: 000000000000002a
[   64.169977] RAX: ffffffffffffffda RBX: 00007ffc830e34d0 RCX: 00007f4851ecb570
[   64.169977] RDX: 0000000000000010 RSI: 00007ffc830e34d0 RDI: 0000000000000005
[   64.169977] RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000000
[   64.169977] R10: 0000000000000006 R11: 0000000000000202 R12: 0000000000000005
[   64.169977] R13: 0000000000000000 R14: 00005619a863f340 R15: 0000000000000000
[   64.169977]  </TASK>

[   64.169977] The buggy address belongs to stack of task ping/2844
[   64.169977]  and is located at offset 88 in frame:
[   64.169977]  ip4_datagram_release_cb+0x0/0x530

[   64.169977] This frame has 1 object:
[   64.169977]  [32, 88) 'fl4'

[   64.169977] The buggy address belongs to the physical page:
[   64.169977] page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xe1ff
[   64.169977] flags: 0x4000000000000000(zone=1)
[   64.169977] raw: 4000000000000000 0000000000000000 ffffea0000387fc8 0000000000000000
[   64.169977] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[   64.169977] page dumped because: kasan: bad access detected

[   64.169977] Memory state around the buggy address:
[   64.169977]  ffff88800e1ffc00: f2 f2 00 00 f3 f3 00 00 00 00 00 00 00 00 00 00
[   64.169977]  ffff88800e1ffc80: 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1 00 00 00
[   64.169977] >ffff88800e1ffd00: 00 00 00 00 f3 f3 f3 f3 f3 00 00 00 00 00 00 00
[   64.169977]                                ^
[   64.169977]  ffff88800e1ffd80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f1 f1
[   64.169977]  ffff88800e1ffe00: f1 f1 00 00 00 00 00 00 00 00 00 00 00 00 00 00
[   64.169977] ==================================================================
[   64.245153] Disabling lock debugging due to kernel taint

After the fix:

ip xfrm policy add src 10.1.1.1/32 dst 10.1.1.2/32 dir out tmpl \
 src fc00::dead:1 dst fc00::dead:2 proto esp reqid 1 mode iptfs \
 level use tmpl src fc00::dead:1 dst fc00::dead:2 proto esp reqid 2 \
 mode transport

Error: Mode in optional template not allowed in outbound policy.

Fixes: d1716d5a44 ("xfrm: add generic iptfs defines and functionality")
Reported-by: syzbot+0ac4d84afe1066a1f3e9@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/6a3ceb94.43b4ff68.30a095.0004.GAE@google.com/T/
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
2026-07-02 09:22:54 +02:00
arch s390: 2026-06-25 10:21:13 -07:00
block block: handle REQ_OP_ZONE_APPEND in __bio_integrity_action 2026-06-24 06:53:25 -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 Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
drivers Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
fs Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
include xfrm: cache the offload ifindex for netlink dumps 2026-07-02 09:12:58 +02:00
init mm.git review status for mm-hotfixes-stable..mm-nonmm-stable 2026-06-21 13:20:19 -07:00
io_uring io_uring-7.2-20260625 2026-06-25 09:53:31 -07:00
ipc kernel-7.2-rc1.misc 2026-06-15 03:05:50 +05:30
kernel block-7.2-20260625 2026-06-25 09:56:47 -07:00
lib Misc fixes: 2026-06-23 16:05:54 -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 block-7.2-20260625 2026-06-25 09:56:47 -07:00
net xfrm: reject optional IPTFS templates in outbound policies 2026-07-02 09:22:54 +02:00
rust Rust changes for v7.2 (addendum) 2026-06-24 15:11:08 -07:00
samples Char/Misc/IIO/FPGA/GPIB/etc driver updates for 7.2-rc1 2026-06-22 12:20:21 -07:00
scripts Second round of Kbuild changes for 7.2 2026-06-25 09:06:12 -07:00
security * add Georgia Garcia as co-maintainer of apparmor 2026-06-24 12:33:40 -07:00
sound dmaengine updates for v7.2 2026-06-23 15:51:14 -07:00
tools Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
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
.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 Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
.pylintrc docs: Move the python libraries to tools/lib/python 2025-11-18 09:22:40 -07:00
.rustfmt.toml
COPYING
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 Including fixes from netfilter and IPsec. 2026-06-25 12:25:36 -07:00
Makefile Second round of Kbuild changes for 7.2 2026-06-25 09:06:12 -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
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* System Administrator - Configuring and troubleshooting
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* 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
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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
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* 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

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--------------------

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

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----------

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* Maintainer Handbook: Documentation/maintainer/index.rst
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---------------

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* Driver API Guide: Documentation/driver-api/index.rst
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* Device Drivers: Documentation/driver-api/infrastructure.rst
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* Device Tree Bindings: Documentation/devicetree/bindings/
* Power Management: Documentation/driver-api/pm/index.rst
* DMA API: Documentation/core-api/dma-api.rst

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-----------------------

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.


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=========================

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