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, 42 insertions, 0 deletions

diff --git a/Documentation/networking/sctp.rst b/Documentation/networking/sctp.rst
new file mode 100644
index 000000000..9f4d9c8a9
--- /dev/null
+++ b/Documentation/networking/sctp.rst
@@ -0,0 +1,42 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=================
+Linux Kernel SCTP
+=================
+
+This is the current BETA release of the Linux Kernel SCTP reference
+implementation.
+
+SCTP (Stream Control Transmission Protocol) is a IP based, message oriented,
+reliable transport protocol, with congestion control, support for
+transparent multi-homing, and multiple ordered streams of messages.
+RFC2960 defines the core protocol.  The IETF SIGTRAN working group originally
+developed the SCTP protocol and later handed the protocol over to the
+Transport Area (TSVWG) working group for the continued evolvement of SCTP as a
+general purpose transport.
+
+See the IETF website (http://www.ietf.org) for further documents on SCTP.
+See http://www.ietf.org/rfc/rfc2960.txt
+
+The initial project goal is to create an Linux kernel reference implementation
+of SCTP that is RFC 2960 compliant and provides an programming interface
+referred to as the  UDP-style API of the Sockets Extensions for SCTP, as
+proposed in IETF Internet-Drafts.
+
+Caveats
+=======
+
+- lksctp can be built as statically or as a module.  However, be aware that
+  module removal of lksctp is not yet a safe activity.
+
+- There is tentative support for IPv6, but most work has gone towards
+  implementation and testing lksctp on IPv4.
+
+
+For more information, please visit the lksctp project website:
+
+   http://www.sf.net/projects/lksctp
+
+Or contact the lksctp developers through the mailing list:
+
+   <linux-sctp@vger.kernel.org>