selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 570 insertions, 0 deletions

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
new file mode 100644
index 000000000..0aa232b11
--- /dev/null
+++ b/Documentation/process/changes.rst
@@ -0,0 +1,570 @@
+.. _changes:
+
+Minimal requirements to compile the Kernel
+++++++++++++++++++++++++++++++++++++++++++
+
+Intro
+=====
+
+This document is designed to provide a list of the minimum levels of
+software necessary to run the current kernel version.
+
+This document is originally based on my "Changes" file for 2.0.x kernels
+and therefore owes credit to the same people as that file (Jared Mauch,
+Axel Boldt, Alessandro Sigala, and countless other users all over the
+'net).
+
+Current Minimal Requirements
+****************************
+
+Upgrade to at **least** these software revisions before thinking you've
+encountered a bug!  If you're unsure what version you're currently
+running, the suggested command should tell you. For a list of the programs
+on your system including their version execute ./scripts/ver_linux
+
+Again, keep in mind that this list assumes you are already functionally
+running a Linux kernel.  Also, not all tools are necessary on all
+systems; obviously, if you don't have any PC Card hardware, for example,
+you probably do not need to concern yourself with pcmciautils.
+
+====================== ===============  ========================================
+        Program        Minimal version       Command to check the version
+====================== ===============  ========================================
+bash                   4.2              bash --version
+bc                     1.06.95          bc --version
+bindgen (optional)     0.71.1           bindgen --version
+binutils               2.30             ld -v
+bison                  2.0              bison --version
+btrfs-progs            0.18             btrfs --version
+Clang/LLVM (optional)  17.0.1           clang --version
+e2fsprogs              1.41.4           e2fsck -V
+flex                   2.5.35           flex --version
+gdb                    7.2              gdb --version
+GNU awk (optional)     5.1.0            gawk --version
+GNU C                  8.1              gcc --version
+GNU make               4.0              make --version
+GNU tar                1.28             tar --version
+GRUB                   0.93             grub --version || grub-install --version
+gtags (optional)       6.6.5            gtags --version
+iptables               1.4.2            iptables -V
+jfsutils               1.1.3            fsck.jfs -V
+kmod                   13               kmod -V
+mcelog                 0.6              mcelog --version
+mkimage (optional)     2017.01          mkimage --version
+nfs-utils              1.0.5            showmount --version
+openssl & libcrypto    1.0.0            openssl version
+pahole                 1.26             pahole --version
+pcmciautils            004              pccardctl -V
+PPP                    2.4.0            pppd --version
+procps                 3.2.0            ps --version
+Python                 3.9.x            python3 --version
+quota-tools            3.09             quota -V
+Rust (optional)        1.85.0           rustc --version
+Sphinx\ [#f1]_         3.4.3            sphinx-build --version
+squashfs-tools         4.0              mksquashfs -version
+udev                   081              udevadm --version
+util-linux             2.10o            mount --version
+xfsprogs               2.6.0            xfs_db -V
+====================== ===============  ========================================
+
+.. [#f1] Sphinx is needed only to build the Kernel documentation
+
+Kernel compilation
+******************
+
+GCC
+---
+
+The gcc version requirements may vary depending on the type of CPU in your
+computer.
+
+Clang/LLVM (optional)
+---------------------
+
+The latest formal release of clang and LLVM utils (according to
+`releases.llvm.org <https://releases.llvm.org>`_) are supported for building
+kernels. Older releases aren't guaranteed to work, and we may drop workarounds
+from the kernel that were used to support older versions. Please see additional
+docs on :ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
+
+Rust (optional)
+---------------
+
+A recent version of the Rust compiler is required.
+
+Please see Documentation/rust/quick-start.rst for instructions on how to
+satisfy the build requirements of Rust support. In particular, the ``Makefile``
+target ``rustavailable`` is useful to check why the Rust toolchain may not
+be detected.
+
+bindgen (optional)
+------------------
+
+``bindgen`` is used to generate the Rust bindings to the C side of the kernel.
+It depends on ``libclang``.
+
+Make
+----
+
+You will need GNU make 4.0 or later to build the kernel.
+
+Bash
+----
+
+Some bash scripts are used for the kernel build.
+Bash 4.2 or newer is needed.
+
+Binutils
+--------
+
+Binutils 2.30 or newer is needed to build the kernel.
+
+pkg-config
+----------
+
+The build system, as of 4.18, requires pkg-config to check for installed
+kconfig tools and to determine flags settings for use in
+'make {g,x}config'.  Previously pkg-config was being used but not
+verified or documented.
+
+Flex
+----
+
+Since Linux 4.16, the build system generates lexical analyzers
+during build.  This requires flex 2.5.35 or later.
+
+
+Bison
+-----
+
+Since Linux 4.16, the build system generates parsers
+during build.  This requires bison 2.0 or later.
+
+pahole
+------
+
+Since Linux 5.2, if CONFIG_DEBUG_INFO_BTF is selected, the build system
+generates BTF (BPF Type Format) from DWARF in vmlinux, a bit later from kernel
+modules as well.  This requires pahole v1.22 or later.
+
+It is found in the 'dwarves' or 'pahole' distro packages or from
+https://fedorapeople.org/~acme/dwarves/.
+
+Perl
+----
+
+You will need perl 5 and the following modules: ``Getopt::Long``,
+``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
+
+Python
+------
+
+Several config options require it: it is required for arm/arm64
+default configs, CONFIG_LTO_CLANG, some DRM optional configs,
+the kernel-doc tool, and docs build (Sphinx), among others.
+
+BC
+--
+
+You will need bc to build kernels 3.10 and higher
+
+
+OpenSSL
+-------
+
+Module signing and external certificate handling use the OpenSSL program and
+crypto library to do key creation and signature generation.
+
+You will need openssl to build kernels 3.7 and higher if module signing is
+enabled.  You will also need openssl development packages to build kernels 4.3
+and higher.
+
+Tar
+---
+
+GNU tar is needed if you want to enable access to the kernel headers via sysfs
+(CONFIG_IKHEADERS).
+
+gtags / GNU GLOBAL (optional)
+-----------------------------
+
+The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
+tag files through ``make gtags``.  This is due to its use of the gtags
+``-C (--directory)`` flag.
+
+mkimage
+-------
+
+This tool is used when building a Flat Image Tree (FIT), commonly used on ARM
+platforms. The tool is available via the ``u-boot-tools`` package or can be
+built from the U-Boot source code. See the instructions at
+https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux
+
+GNU AWK
+-------
+
+GNU AWK is needed if you want kernel builds to generate address range data for
+builtin modules (CONFIG_BUILTIN_MODULE_RANGES).
+
+System utilities
+****************
+
+Architectural changes
+---------------------
+
+DevFS has been obsoleted in favour of udev
+(https://www.kernel.org/pub/linux/utils/kernel/hotplug/)
+
+32-bit UID support is now in place.  Have fun!
+
+Linux documentation for functions is transitioning to inline
+documentation via specially-formatted comments near their
+definitions in the source.  These comments can be combined with ReST
+files in the Documentation/ directory to make enriched documentation, which can
+then be converted to PostScript, HTML, LaTex, ePUB and PDF files.
+In order to convert from ReST format to a format of your choice, you'll need
+Sphinx.
+
+Util-linux
+----------
+
+New versions of util-linux provide ``fdisk`` support for larger disks,
+support new options to mount, recognize more supported partition
+types, and similar goodies.
+You'll probably want to upgrade.
+
+Ksymoops
+--------
+
+If the unthinkable happens and your kernel oopses, you may need the
+ksymoops tool to decode it, but in most cases you don't.
+It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
+that it produces readable dumps that can be used as-is (this also
+produces better output than ksymoops).  If for some reason your kernel
+is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
+reproduce the Oops with that option, then you can still decode that Oops
+with ksymoops.
+
+Mkinitrd
+--------
+
+These changes to the ``/lib/modules`` file tree layout also require that
+mkinitrd be upgraded.
+
+E2fsprogs
+---------
+
+The latest version of ``e2fsprogs`` fixes several bugs in fsck and
+debugfs.  Obviously, it's a good idea to upgrade.
+
+JFSutils
+--------
+
+The ``jfsutils`` package contains the utilities for the file system.
+The following utilities are available:
+
+- ``fsck.jfs`` - initiate replay of the transaction log, and check
+  and repair a JFS formatted partition.
+
+- ``mkfs.jfs`` - create a JFS formatted partition.
+
+- other file system utilities are also available in this package.
+
+Xfsprogs
+--------
+
+The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
+``xfs_repair`` utilities, among others, for the XFS filesystem.  It is
+architecture independent and any version from 2.0.0 onward should
+work correctly with this version of the XFS kernel code (2.6.0 or
+later is recommended, due to some significant improvements).
+
+PCMCIAutils
+-----------
+
+PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
+PCMCIA sockets at system startup and loads the appropriate modules
+for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
+subsystem is used.
+
+Quota-tools
+-----------
+
+Support for 32 bit uid's and gid's is required if you want to use
+the newer version 2 quota format.  Quota-tools version 3.07 and
+newer has this support.  Use the recommended version or newer
+from the table above.
+
+Intel IA32 microcode
+--------------------
+
+A driver has been added to allow updating of Intel IA32 microcode,
+accessible as a normal (misc) character device.  If you are not using
+udev you may need to::
+
+  mkdir /dev/cpu
+  mknod /dev/cpu/microcode c 10 184
+  chmod 0644 /dev/cpu/microcode
+
+as root before you can use this.  You'll probably also want to
+get the user-space microcode_ctl utility to use with this.
+
+udev
+----
+
+``udev`` is a userspace application for populating ``/dev`` dynamically with
+only entries for devices actually present. ``udev`` replaces the basic
+functionality of devfs, while allowing persistent device naming for
+devices.
+
+FUSE
+----
+
+Needs libfuse 2.4.0 or later.  Absolute minimum is 2.3.0 but mount
+options ``direct_io`` and ``kernel_cache`` won't work.
+
+Networking
+**********
+
+General changes
+---------------
+
+If you have advanced network configuration needs, you should probably
+consider using the network tools from ip-route2.
+
+Packet Filter / NAT
+-------------------
+The packet filtering and NAT code uses the same tools like the previous 2.4.x
+kernel series (iptables).  It still includes backwards-compatibility modules
+for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
+
+PPP
+---
+
+The PPP driver has been restructured to support multilink and to
+enable it to operate over diverse media layers.  If you use PPP,
+upgrade pppd to at least 2.4.0.
+
+If you are not using udev, you must have the device file /dev/ppp
+which can be made by::
+
+  mknod /dev/ppp c 108 0
+
+as root.
+
+NFS-utils
+---------
+
+In ancient (2.4 and earlier) kernels, the nfs server needed to know
+about any client that expected to be able to access files via NFS.  This
+information would be given to the kernel by ``mountd`` when the client
+mounted the filesystem, or by ``exportfs`` at system startup.  exportfs
+would take information about active clients from ``/var/lib/nfs/rmtab``.
+
+This approach is quite fragile as it depends on rmtab being correct
+which is not always easy, particularly when trying to implement
+fail-over.  Even when the system is working well, ``rmtab`` suffers from
+getting lots of old entries that never get removed.
+
+With modern kernels we have the option of having the kernel tell mountd
+when it gets a request from an unknown host, and mountd can give
+appropriate export information to the kernel.  This removes the
+dependency on ``rmtab`` and means that the kernel only needs to know about
+currently active clients.
+
+To enable this new functionality, you need to::
+
+  mount -t nfsd nfsd /proc/fs/nfsd
+
+before running exportfs or mountd.  It is recommended that all NFS
+services be protected from the internet-at-large by a firewall where
+that is possible.
+
+mcelog
+------
+
+On x86 kernels the mcelog utility is needed to process and log machine check
+events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
+reported by the CPU. Processing them is strongly encouraged.
+
+Kernel documentation
+********************
+
+Sphinx
+------
+
+Please see :ref:`sphinx_install` in Documentation/doc-guide/sphinx.rst
+for details about Sphinx requirements.
+
+rustdoc
+-------
+
+``rustdoc`` is used to generate the documentation for Rust code. Please see
+Documentation/rust/general-information.rst for more information.
+
+Getting updated software
+========================
+
+Kernel compilation
+******************
+
+gcc
+---
+
+- <ftp://ftp.gnu.org/gnu/gcc/>
+
+Clang/LLVM
+----------
+
+- :ref:`Getting LLVM <getting_llvm>`.
+
+Rust
+----
+
+- Documentation/rust/quick-start.rst.
+
+bindgen
+-------
+
+- Documentation/rust/quick-start.rst.
+
+Make
+----
+
+- <ftp://ftp.gnu.org/gnu/make/>
+
+Bash
+----
+
+- <ftp://ftp.gnu.org/gnu/bash/>
+
+Binutils
+--------
+
+- <https://www.kernel.org/pub/linux/devel/binutils/>
+
+Flex
+----
+
+- <https://github.com/westes/flex/releases>
+
+Bison
+-----
+
+- <ftp://ftp.gnu.org/gnu/bison/>
+
+OpenSSL
+-------
+
+- <https://www.openssl.org/>
+
+System utilities
+****************
+
+Util-linux
+----------
+
+- <https://www.kernel.org/pub/linux/utils/util-linux/>
+
+Kmod
+----
+
+- <https://www.kernel.org/pub/linux/utils/kernel/kmod/>
+- <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
+
+Ksymoops
+--------
+
+- <https://www.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
+
+Mkinitrd
+--------
+
+- <https://code.launchpad.net/initrd-tools/main>
+
+E2fsprogs
+---------
+
+- <https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/>
+- <https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/>
+
+JFSutils
+--------
+
+- <https://jfs.sourceforge.net/>
+
+Xfsprogs
+--------
+
+- <https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git>
+- <https://www.kernel.org/pub/linux/utils/fs/xfs/xfsprogs/>
+
+Pcmciautils
+-----------
+
+- <https://www.kernel.org/pub/linux/utils/kernel/pcmcia/>
+
+Quota-tools
+-----------
+
+- <https://sourceforge.net/projects/linuxquota/>
+
+
+Intel P6 microcode
+------------------
+
+- <https://downloadcenter.intel.com/>
+
+udev
+----
+
+- <https://www.freedesktop.org/software/systemd/man/udev.html>
+
+FUSE
+----
+
+- <https://github.com/libfuse/libfuse/releases>
+
+mcelog
+------
+
+- <https://www.mcelog.org/>
+
+Networking
+**********
+
+PPP
+---
+
+- <https://download.samba.org/pub/ppp/>
+- <https://git.ozlabs.org/?p=ppp.git>
+- <https://github.com/paulusmack/ppp/>
+
+NFS-utils
+---------
+
+- <https://sourceforge.net/project/showfiles.php?group_id=14>
+- <https://nfs.sourceforge.net/>
+
+Iptables
+--------
+
+- <https://netfilter.org/projects/iptables/index.html>
+
+Ip-route2
+---------
+
+- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
+
+OProfile
+--------
+
+- <https://oprofile.sf.net/download/>
+
+Kernel documentation
+********************
+
+Sphinx
+------
+
+- <https://www.sphinx-doc.org/>