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, 82 insertions, 0 deletions

diff --git a/ipc/compat.c b/ipc/compat.c
new file mode 100644
index 000000000..5ab822592
--- /dev/null
+++ b/ipc/compat.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * 32 bit compatibility code for System V IPC
+ *
+ * Copyright (C) 1997,1998	Jakub Jelinek (jj@sunsite.mff.cuni.cz)
+ * Copyright (C) 1997		David S. Miller (davem@caip.rutgers.edu)
+ * Copyright (C) 1999		Arun Sharma <arun.sharma@intel.com>
+ * Copyright (C) 2000		VA Linux Co
+ * Copyright (C) 2000		Don Dugger <n0ano@valinux.com>
+ * Copyright (C) 2000           Hewlett-Packard Co.
+ * Copyright (C) 2000           David Mosberger-Tang <davidm@hpl.hp.com>
+ * Copyright (C) 2000           Gerhard Tonn (ton@de.ibm.com)
+ * Copyright (C) 2000-2002      Andi Kleen, SuSE Labs (x86-64 port)
+ * Copyright (C) 2000		Silicon Graphics, Inc.
+ * Copyright (C) 2001		IBM
+ * Copyright (C) 2004		IBM Deutschland Entwicklung GmbH, IBM Corporation
+ * Copyright (C) 2004		Arnd Bergmann (arnd@arndb.de)
+ *
+ * This code is collected from the versions for sparc64, mips64, s390x, ia64,
+ * ppc64 and x86_64, all of which are based on the original sparc64 version
+ * by Jakub Jelinek.
+ *
+ */
+#include <linux/compat.h>
+#include <linux/errno.h>
+#include <linux/highuid.h>
+#include <linux/init.h>
+#include <linux/msg.h>
+#include <linux/shm.h>
+#include <linux/syscalls.h>
+#include <linux/ptrace.h>
+
+#include <linux/mutex.h>
+#include <linux/uaccess.h>
+
+#include "util.h"
+
+int get_compat_ipc64_perm(struct ipc64_perm *to,
+			  struct compat_ipc64_perm __user *from)
+{
+	struct compat_ipc64_perm v;
+	if (copy_from_user(&v, from, sizeof(v)))
+		return -EFAULT;
+	to->uid = v.uid;
+	to->gid = v.gid;
+	to->mode = v.mode;
+	return 0;
+}
+
+int get_compat_ipc_perm(struct ipc64_perm *to,
+			struct compat_ipc_perm __user *from)
+{
+	struct compat_ipc_perm v;
+	if (copy_from_user(&v, from, sizeof(v)))
+		return -EFAULT;
+	to->uid = v.uid;
+	to->gid = v.gid;
+	to->mode = v.mode;
+	return 0;
+}
+
+void to_compat_ipc64_perm(struct compat_ipc64_perm *to, struct ipc64_perm *from)
+{
+	to->key = from->key;
+	to->uid = from->uid;
+	to->gid = from->gid;
+	to->cuid = from->cuid;
+	to->cgid = from->cgid;
+	to->mode = from->mode;
+	to->seq = from->seq;
+}
+
+void to_compat_ipc_perm(struct compat_ipc_perm *to, struct ipc64_perm *from)
+{
+	to->key = from->key;
+	SET_UID(to->uid, from->uid);
+	SET_GID(to->gid, from->gid);
+	SET_UID(to->cuid, from->cuid);
+	SET_GID(to->cgid, from->cgid);
+	to->mode = from->mode;
+	to->seq = from->seq;
+}