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Linux kernel source tree
copy_to_user_state_extra() only holds a reference to the outer xfrm_state.
That does not pin x->xso.dev. NETDEV_DOWN and NETDEV_UNREGISTER can race
through xfrm_dev_state_flush(), xfrm_state_delete(), and
xfrm_dev_state_free(), which clears xso->dev and drops the netdev
reference before the GETSA dump reaches xso_to_xuo() and reads
xso->dev->ifindex.
The buggy scenario involves two paths, with each column showing the order
within that path:
XFRM_MSG_GETSA dump path: NETDEV teardown path:
1. xfrm_get_sa() gets xfrm_state 1. xfrm_dev_state_flush() finds x
2. copy_to_user_state_extra() sees 2. xfrm_state_delete() removes x
x->xso.dev from the SAD
3. copy_user_offload() calls 3. xfrm_dev_state_free() clears
xso_to_xuo() xso->dev
4. xso->dev->ifindex dereferences 4. netdev_put() drops the device
a detached net_device reference
Avoid following the live net_device from the dump paths. Cache the
attached ifindex in xfrm_dev_offload when state or policy offload is bound
to a device, and serialize that snapshot instead. This preserves the
user-visible XFRMA_OFFLOAD_DEV value without depending on the embedded
net_device lifetime.
Validation reproduced this kernel report:
Oops: general protection fault
Call Trace:
<TASK>
copy_to_user_state_extra+0xb8d/0x1370 [xfrm_user]
? __pfx_copy_to_user_state_extra+0x10/0x10 [xfrm_user]
? __asan_memset+0x23/0x50
? srso_alias_return_thunk+0x5/0xfbef5
? __alloc_skb+0x342/0x960
? srso_alias_return_thunk+0x5/0xfbef5
? __asan_memset+0x23/0x50
? srso_alias_return_thunk+0x5/0xfbef5
? __nlmsg_put+0x147/0x1b0
dump_one_state+0x1c7/0x3e0 [xfrm_user]
xfrm_state_netlink+0xcb/0x130 [xfrm_user]
? __pfx_xfrm_state_netlink+0x10/0x10 [xfrm_user]
? srso_alias_return_thunk+0x5/0xfbef5
? xfrm_user_state_lookup.constprop.0+0x230/0x310 [xfrm_user]
xfrm_get_sa+0x102/0x250 [xfrm_user]
? __pfx_xfrm_get_sa+0x10/0x10 [xfrm_user]
xfrm_user_rcv_msg+0x504/0xaa0 [xfrm_user]
? __pfx_xfrm_user_rcv_msg+0x10/0x10 [xfrm_user]
? srso_alias_return_thunk+0x5/0xfbef5
? stack_trace_save+0x8e/0xc0
? __pfx_stack_trace_save+0x10/0x10
netlink_rcv_skb+0x11f/0x350
? __pfx_xfrm_user_rcv_msg+0x10/0x10 [xfrm_user]
? __pfx_netlink_rcv_skb+0x10/0x10
? __pfx_mutex_lock+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
xfrm_netlink_rcv+0x65/0x80 [xfrm_user]
netlink_unicast+0x600/0x870
? __pfx_netlink_unicast+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
? __pfx_stack_trace_save+0x10/0x10
netlink_sendmsg+0x75d/0xc10
? __pfx_netlink_sendmsg+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
____sys_sendmsg+0x77a/0x900
? srso_alias_return_thunk+0x5/0xfbef5
? __pfx_____sys_sendmsg+0x10/0x10
? __pfx_copy_msghdr_from_user+0x10/0x10
? release_sock+0x1a/0x1d0
? srso_alias_return_thunk+0x5/0xfbef5
? netlink_insert+0x143/0xec0
___sys_sendmsg+0xff/0x180
? __pfx____sys_sendmsg+0x10/0x10
? _raw_spin_lock_irqsave+0x85/0xe0
? do_getsockname+0xf9/0x170
? srso_alias_return_thunk+0x5/0xfbef5
? fdget+0x53/0x3b0
__sys_sendmsg+0x111/0x1a0
? __pfx___sys_sendmsg+0x10/0x10
? srso_alias_return_thunk+0x5/0xfbef5
? __sys_getsockname+0x8c/0x100
do_syscall_64+0x102/0x5a0
entry_SYSCALL_64_after_hwframe+0x77/0x7f
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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