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, 65 insertions, 0 deletions

diff --git a/fs/udf/udf_i.h b/fs/udf/udf_i.h
new file mode 100644
index 000000000..fdaa88c49
--- /dev/null
+++ b/fs/udf/udf_i.h
@@ -0,0 +1,65 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _UDF_I_H
+#define _UDF_I_H
+
+struct extent_position {
+	struct buffer_head *bh;
+	uint32_t offset;
+	struct kernel_lb_addr block;
+};
+
+struct udf_ext_cache {
+	/* Extent position */
+	struct extent_position epos;
+	/* Start logical offset in bytes */
+	loff_t lstart;
+};
+
+/*
+ * The i_data_sem and i_mutex serve for protection of allocation information
+ * of a regular files and symlinks. This includes all extents belonging to
+ * the file/symlink, a fact whether data are in-inode or in external data
+ * blocks, preallocation, goal block information... When extents are read,
+ * i_mutex or i_data_sem must be held (for reading is enough in case of
+ * i_data_sem). When extents are changed, i_data_sem must be held for writing
+ * and also i_mutex must be held.
+ *
+ * For directories i_mutex is used for all the necessary protection.
+ */
+
+struct udf_inode_info {
+	struct timespec64	i_crtime;
+	/* Physical address of inode */
+	struct kernel_lb_addr		i_location;
+	__u64			i_unique;
+	__u32			i_lenEAttr;
+	__u32			i_lenAlloc;
+	__u64			i_lenExtents;
+	__u32			i_next_alloc_block;
+	__u32			i_next_alloc_goal;
+	__u32			i_checkpoint;
+	__u32			i_extraPerms;
+	unsigned		i_alloc_type : 3;
+	unsigned		i_efe : 1;	/* extendedFileEntry */
+	unsigned		i_use : 1;	/* unallocSpaceEntry */
+	unsigned		i_strat4096 : 1;
+	unsigned		i_streamdir : 1;
+	unsigned		i_hidden : 1;	/* hidden system inode */
+	unsigned		reserved : 24;
+	__u8			*i_data;
+	struct kernel_lb_addr	i_locStreamdir;
+	__u64			i_lenStreams;
+	struct rw_semaphore	i_data_sem;
+	struct mapping_metadata_bhs i_metadata_bhs;
+	struct udf_ext_cache cached_extent;
+	/* Spinlock for protecting extent cache */
+	spinlock_t i_extent_cache_lock;
+	struct inode vfs_inode;
+};
+
+static inline struct udf_inode_info *UDF_I(struct inode *inode)
+{
+	return container_of(inode, struct udf_inode_info, vfs_inode);
+}
+
+#endif /* _UDF_I_H) */