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Zhu Yanjun 35744ab3d0 RDMA/rxe: Fix a use-after-free problem in rxe_mmap
rxe_mmap() removes a rxe_mmap_info struct from the pending_mmaps list
and releases pending_lock while the struct's kref is still at 1:

   list_del_init(&ip->pending_mmaps);
   spin_unlock_bh(&rxe->pending_lock);   /* ref == 1, no lock held */
   ret = remap_vmalloc_range(vma, ip->obj, 0);  /* walks PTEs */
   [...]
   rxe_vma_open(vma);                    /* kref_get, ref → 2 */
   remap_vmalloc_range_partial() walks PTEs without any lock.

A concurrent DESTROY_CQ ioctl on another CPU calls:

    kref_put(&q->ip->ref, rxe_mmap_release)   /* ref 1→0 */
    vfree(ip->obj)   /* clears vmalloc PTEs mid-walk */
    kfree(ip)        /* frees rxe_mmap_info */

This yields:

   1. Kernel crash, vmalloc_to_page() returns NULL when vfree wins the
   per-PTE race -> vm_insert_page(NULL) → GPF in validate_page_before_insert

   2. Page UAF, vmalloc_to_page() reads a stale PTE before vfree clears
   it. User VMA holds a PTE to a free'd page which might eventually get
   reallocated later by vmalloc which allows the attacker to get a clean
   page-level UAF.

   It is worth noting that even though a page-level UAF is possible given
   the strong primitive, it is statistically very difficult to achieve
   given the very short time window (after the last insert_page and before
   the kref_get).

The call trace are as below:

  Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
  KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
  CPU: 0 UID: 1000 PID: 413 Comm: poc Not tainted 7.0.0-rc5-dirty #28 PREEMPT(lazy)
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
  RIP: 0010:validate_page_before_insert+0x32/0x300
  Code: e5 41 57 41 56 49 89 fe 41 55 41 54 53 48 89 f3 e8 93 b5 a3 ff 48 8d 7b 08 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 7b 02 00 00 4c 8b 63 08 31 ff 4d 89 e5 41 83 e5
  RSP: 0018:ffff88811b15f2f0 EFLAGS: 00000202
  RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
  RDX: 0000000000000001 RSI: 0000000000000000 RDI: 0000000000000008
  RBP: ffff88811b15f318 R08: 0000000000000000 R09: 0000000000000000
  R10: 0000000000000000 R11: 0000000000000000 R12: ffff8881181eee00
  R13: 0000000000000000 R14: ffff8881181eee00 R15: ffff8881181eee20
  FS:  00007b1e000f76c0(0000) GS:ffff8884268e0000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
  CR2: 00007b1e00a24ac0 CR3: 0000000116eb3000 CR4: 00000000000006f0
  Call Trace:
   <TASK>
   insert_page+0x8f/0x190
   ? __pfx_insert_page+0x10/0x10
   ? kasan_save_alloc_info+0x38/0x60
   vm_insert_page+0x2e7/0x400
   remap_vmalloc_range_partial+0x212/0x3e0
   remap_vmalloc_range+0x6e/0xb0
   ? __kasan_check_write+0x14/0x30
   rxe_mmap+0x2e9/0x5d0
   ib_uverbs_mmap+0x1ad/0x2c0
   __mmap_region+0x12c2/0x2ad0
   ? __pfx___mmap_region+0x10/0x10
   ? __sanitizer_cov_trace_switch+0x58/0xb0
   ? mas_prev_slot+0x360/0x39c0
   ? __sanitizer_cov_trace_switch+0x58/0xb0
   ? mas_next_slot+0x1e5b/0x2f40
   ? __sanitizer_cov_trace_cmp8+0x18/0x30
   ? unmapped_area_topdown+0x4dd/0x610
   ? kfree+0x1b1/0x440
   ? free_cpumask_var+0x16/0x30
   ? __kasan_slab_free+0x7d/0xa0
   ? __sanitizer_cov_trace_cmp8+0x18/0x30
   mmap_region+0x2e6/0x3c0
   do_mmap+0xa3e/0x12a0
   ? __pfx_do_mmap+0x10/0x10
   ? __kasan_check_write+0x14/0x30
   ? down_write_killable+0xba/0x160
   ? __pfx_down_write_killable+0x10/0x10
   ? __sanitizer_cov_trace_cmp4+0x16/0x30
   vm_mmap_pgoff+0x2d4/0x4a0
   ? __pfx_vm_mmap_pgoff+0x10/0x10
   ? fget+0x1bf/0x270
   ksys_mmap_pgoff+0x40c/0x690
   ? __sanitizer_cov_trace_const_cmp4+0x16/0x30
   ? __pfx_ksys_mmap_pgoff+0x10/0x10
   ? __kasan_check_write+0x14/0x30
   ? _raw_spin_trylock+0xbb/0x130
   ? __pfx__raw_spin_trylock+0x10/0x10
   __x64_sys_mmap+0x135/0x1e0
   x64_sys_call+0x1c14/0x2790
   do_syscall_64+0xd2/0x1050
   ? rcu_core+0x352/0x7d0
   ? rcu_core_si+0xe/0x20
   ? handle_softirqs+0x1aa/0x650
   ? __sanitizer_cov_trace_cmp4+0x16/0x30
   ? fpregs_assert_state_consistent+0xe1/0x160
   ? irqentry_exit+0xb1/0x670
   entry_SYSCALL_64_after_hwframe+0x76/0x7e

Link: https://patch.msgid.link/r/20260515002537.6209-1-yanjun.zhu@linux.dev
Reported-and-tested-by: nasm <n4sm@protonmail.com>
Suggested-by: nasm <n4sm@protonmail.com>
Fixes: 8700e3e7c4 ("Soft RoCE driver")
Signed-off-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
2026-05-25 11:25:16 -03:00
arch sh fixes for v7.1 2026-05-03 08:58:42 -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: 2026-05-02 12:31:43 -07:00
Documentation Including fixes from netfilter. 2026-04-30 08:45:43 -07:00
drivers RDMA/rxe: Fix a use-after-free problem in rxe_mmap 2026-05-25 11:25:16 -03:00
fs Description for this pull request: 2026-05-02 12:25:57 -07:00
include RDMA/bnxt_re: Enable app allocated QPs 2026-05-24 12:32:21 -03:00
init memblock: updates for 7.0-rc1 2026-04-18 11:29:14 -07:00
io_uring io_uring-7.1-20260430 2026-05-01 11:01:31 -07:00
ipc Convert 'alloc_obj' family to use the new default GFP_KERNEL argument 2026-02-21 17:09:51 -08:00
kernel Fix lockup in requeue-PI during signal/timeout wakeups, 2026-05-03 08:17:09 -07:00
lib 20 hotfixes. All are for MM (and for MMish maintainers). 9 are cc:stable 2026-05-01 08:45:23 -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 fixes for 7.1-rc1 2026-05-03 08:19:57 -07:00
net net/sched: cls_flower: revert unintended changes 2026-04-30 13:47:01 +02:00
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 selinux: fix avdcache auditing 2026-04-28 18:13:58 -04:00
sound ALSA: hda/tas2781: Fix incorrect bit update for non-book-zero or book 0 pages >1 2026-04-29 07:51:17 +02:00
tools selftest/rxe: Add selftests for perf 2026-05-18 04:58:41 -04:00
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 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 kbuild: rust: provide an option to inline C helpers into Rust 2026-03-30 02:03:52 +02:00
.mailmap drm fixes for 7.1-rc2 2026-05-01 16:56:08 -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 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 drm fixes for 7.1-rc2 2026-05-01 16:56:08 -07:00
Makefile Linux 7.1-rc2 2026-05-03 14:21:25 -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