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, 127 insertions, 0 deletions

diff --git a/fs/jffs2/xattr.h b/fs/jffs2/xattr.h
new file mode 100644
index 000000000..7e7de093e
--- /dev/null
+++ b/fs/jffs2/xattr.h
@@ -0,0 +1,127 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright © 2006  NEC Corporation
+ *
+ * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
+ *
+ * For licensing information, see the file 'LICENCE' in this directory.
+ *
+ */
+
+#ifndef _JFFS2_FS_XATTR_H_
+#define _JFFS2_FS_XATTR_H_
+
+#include <linux/xattr.h>
+#include <linux/list.h>
+
+#define JFFS2_XFLAGS_HOT	(0x01)	/* This datum is HOT */
+#define JFFS2_XFLAGS_BIND	(0x02)	/* This datum is not reclaimed */
+#define JFFS2_XFLAGS_DEAD	(0x40)	/* This datum is already dead */
+#define JFFS2_XFLAGS_INVALID	(0x80)	/* This datum contains crc error */
+
+struct jffs2_xattr_datum
+{
+	void *always_null;
+	struct jffs2_raw_node_ref *node;
+	uint8_t class;
+	uint8_t flags;
+	uint16_t xprefix;		/* see JFFS2_XATTR_PREFIX_* */
+
+	struct list_head xindex;	/* chained from c->xattrindex[n] */
+	atomic_t refcnt;		/* # of xattr_ref refers this */
+	uint32_t xid;
+	uint32_t version;
+
+	uint32_t data_crc;
+	uint32_t hashkey;
+	char *xname;		/* XATTR name without prefix */
+	uint32_t name_len;	/* length of xname */
+	char *xvalue;		/* XATTR value */
+	uint32_t value_len;	/* length of xvalue */
+};
+
+struct jffs2_inode_cache;
+struct jffs2_xattr_ref
+{
+	void *always_null;
+	struct jffs2_raw_node_ref *node;
+	uint8_t class;
+	uint8_t flags;		/* Currently unused */
+	u16 unused;
+
+	uint32_t xseqno;
+	union {
+		struct jffs2_inode_cache *ic;	/* reference to jffs2_inode_cache */
+		uint32_t ino;			/* only used in scanning/building  */
+	};
+	union {
+		struct jffs2_xattr_datum *xd;	/* reference to jffs2_xattr_datum */
+		uint32_t xid;			/* only used in sccanning/building */
+	};
+	struct jffs2_xattr_ref *next;		/* chained from ic->xref_list */
+};
+
+#define XREF_DELETE_MARKER	(0x00000001)
+static inline int is_xattr_ref_dead(struct jffs2_xattr_ref *ref)
+{
+	return ((ref->xseqno & XREF_DELETE_MARKER) != 0);
+}
+
+#ifdef CONFIG_JFFS2_FS_XATTR
+
+extern void jffs2_init_xattr_subsystem(struct jffs2_sb_info *c);
+extern int jffs2_build_xattr_subsystem(struct jffs2_sb_info *c);
+extern void jffs2_clear_xattr_subsystem(struct jffs2_sb_info *c);
+
+extern struct jffs2_xattr_datum *jffs2_setup_xattr_datum(struct jffs2_sb_info *c,
+							 uint32_t xid, uint32_t version);
+
+extern void jffs2_xattr_do_crccheck_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic);
+extern void jffs2_xattr_delete_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic);
+extern void jffs2_xattr_free_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic);
+
+extern int jffs2_garbage_collect_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd,
+					     struct jffs2_raw_node_ref *raw);
+extern int jffs2_garbage_collect_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref,
+					   struct jffs2_raw_node_ref *raw);
+extern int jffs2_verify_xattr(struct jffs2_sb_info *c);
+extern void jffs2_release_xattr_datum(struct jffs2_sb_info *c, struct jffs2_xattr_datum *xd);
+extern void jffs2_release_xattr_ref(struct jffs2_sb_info *c, struct jffs2_xattr_ref *ref);
+
+extern int do_jffs2_getxattr(struct inode *inode, int xprefix, const char *xname,
+			     char *buffer, size_t size);
+extern int do_jffs2_setxattr(struct inode *inode, int xprefix, const char *xname,
+			     const char *buffer, size_t size, int flags);
+
+extern const struct xattr_handler * const jffs2_xattr_handlers[];
+extern const struct xattr_handler jffs2_user_xattr_handler;
+extern const struct xattr_handler jffs2_trusted_xattr_handler;
+
+extern ssize_t jffs2_listxattr(struct dentry *, char *, size_t);
+
+#else
+
+#define jffs2_init_xattr_subsystem(c)
+#define jffs2_build_xattr_subsystem(c)		(0)
+#define jffs2_clear_xattr_subsystem(c)
+
+#define jffs2_xattr_do_crccheck_inode(c, ic)
+#define jffs2_xattr_delete_inode(c, ic)
+#define jffs2_xattr_free_inode(c, ic)
+#define jffs2_verify_xattr(c)			(1)
+
+#define jffs2_xattr_handlers	NULL
+#define jffs2_listxattr		NULL
+
+#endif /* CONFIG_JFFS2_FS_XATTR */
+
+#ifdef CONFIG_JFFS2_FS_SECURITY
+extern int jffs2_init_security(struct inode *inode, struct inode *dir,
+			       const struct qstr *qstr);
+extern const struct xattr_handler jffs2_security_xattr_handler;
+#else
+#define jffs2_init_security(inode,dir,qstr)	(0)
+#endif /* CONFIG_JFFS2_FS_SECURITY */
+
+#endif /* _JFFS2_FS_XATTR_H_ */