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, 49 insertions, 0 deletions

diff --git a/fs/smb/server/glob.h b/fs/smb/server/glob.h
new file mode 100644
index 000000000..4ea187af2
--- /dev/null
+++ b/fs/smb/server/glob.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __KSMBD_GLOB_H
+#define __KSMBD_GLOB_H
+
+#include <linux/ctype.h>
+
+#include "unicode.h"
+#include "vfs_cache.h"
+
+extern int ksmbd_debug_types;
+
+#define KSMBD_DEBUG_SMB		BIT(0)
+#define KSMBD_DEBUG_AUTH	BIT(1)
+#define KSMBD_DEBUG_VFS		BIT(2)
+#define KSMBD_DEBUG_OPLOCK      BIT(3)
+#define KSMBD_DEBUG_IPC         BIT(4)
+#define KSMBD_DEBUG_CONN        BIT(5)
+#define KSMBD_DEBUG_RDMA        BIT(6)
+#define KSMBD_DEBUG_ALL         (KSMBD_DEBUG_SMB | KSMBD_DEBUG_AUTH |	\
+				KSMBD_DEBUG_VFS | KSMBD_DEBUG_OPLOCK |	\
+				KSMBD_DEBUG_IPC | KSMBD_DEBUG_CONN |	\
+				KSMBD_DEBUG_RDMA)
+
+#ifdef pr_fmt
+#undef pr_fmt
+#endif
+
+#ifdef SUBMOD_NAME
+#define pr_fmt(fmt)	"ksmbd: " SUBMOD_NAME ": " fmt
+#else
+#define pr_fmt(fmt)	"ksmbd: " fmt
+#endif
+
+#define ksmbd_debug(type, fmt, ...)				\
+	do {							\
+		if (ksmbd_debug_types & KSMBD_DEBUG_##type)	\
+			pr_info(fmt, ##__VA_ARGS__);		\
+	} while (0)
+
+#define UNICODE_LEN(x)		((x) * 2)
+
+#define KSMBD_DEFAULT_GFP	(GFP_KERNEL | __GFP_RETRY_MAYFAIL)
+
+#endif /* __KSMBD_GLOB_H */