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, 314 insertions, 0 deletions

diff --git a/fs/btrfs/tests/btrfs-tests.c b/fs/btrfs/tests/btrfs-tests.c
new file mode 100644
index 000000000..6287d9403
--- /dev/null
+++ b/fs/btrfs/tests/btrfs-tests.c
@@ -0,0 +1,314 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2013 Fusion IO.  All rights reserved.
+ */
+
+#include <linux/fs.h>
+#include <linux/mount.h>
+#include <linux/pseudo_fs.h>
+#include <linux/magic.h>
+#include "btrfs-tests.h"
+#include "../ctree.h"
+#include "../free-space-cache.h"
+#include "../free-space-tree.h"
+#include "../transaction.h"
+#include "../volumes.h"
+#include "../disk-io.h"
+#include "../qgroup.h"
+#include "../block-group.h"
+#include "../fs.h"
+
+static struct vfsmount *test_mnt = NULL;
+
+const char *test_error[] = {
+	[TEST_ALLOC_FS_INFO]	     = "cannot allocate fs_info",
+	[TEST_ALLOC_ROOT]	     = "cannot allocate root",
+	[TEST_ALLOC_EXTENT_BUFFER]   = "cannot extent buffer",
+	[TEST_ALLOC_PATH]	     = "cannot allocate path",
+	[TEST_ALLOC_INODE]	     = "cannot allocate inode",
+	[TEST_ALLOC_BLOCK_GROUP]     = "cannot allocate block group",
+	[TEST_ALLOC_EXTENT_MAP]      = "cannot allocate extent map",
+	[TEST_ALLOC_CHUNK_MAP]       = "cannot allocate chunk map",
+	[TEST_ALLOC_IO_CONTEXT]	     = "cannot allocate io context",
+	[TEST_ALLOC_TRANSACTION]     = "cannot allocate transaction",
+};
+
+static const struct super_operations btrfs_test_super_ops = {
+	.alloc_inode	= btrfs_alloc_inode,
+	.destroy_inode	= btrfs_test_destroy_inode,
+};
+
+
+static int btrfs_test_init_fs_context(struct fs_context *fc)
+{
+	struct pseudo_fs_context *ctx = init_pseudo(fc, BTRFS_TEST_MAGIC);
+	if (!ctx)
+		return -ENOMEM;
+	ctx->ops = &btrfs_test_super_ops;
+	return 0;
+}
+
+static struct file_system_type test_type = {
+	.name		= "btrfs_test_fs",
+	.init_fs_context = btrfs_test_init_fs_context,
+	.kill_sb	= kill_anon_super,
+};
+
+struct inode *btrfs_new_test_inode(void)
+{
+	struct inode *inode;
+
+	inode = new_inode(test_mnt->mnt_sb);
+	if (!inode)
+		return NULL;
+
+	inode->i_mode = S_IFREG;
+	btrfs_set_inode_number(BTRFS_I(inode), BTRFS_FIRST_FREE_OBJECTID);
+	inode_init_owner(&nop_mnt_idmap, inode, NULL, S_IFREG);
+
+	return inode;
+}
+
+static int btrfs_init_test_fs(void)
+{
+	int ret;
+
+	ret = register_filesystem(&test_type);
+	if (ret) {
+		printk(KERN_ERR "btrfs: cannot register test file system\n");
+		return ret;
+	}
+
+	test_mnt = kern_mount(&test_type);
+	if (IS_ERR(test_mnt)) {
+		printk(KERN_ERR "btrfs: cannot mount test file system\n");
+		unregister_filesystem(&test_type);
+		return PTR_ERR(test_mnt);
+	}
+	return 0;
+}
+
+static void btrfs_destroy_test_fs(void)
+{
+	kern_unmount(test_mnt);
+	unregister_filesystem(&test_type);
+}
+
+struct btrfs_device *btrfs_alloc_dummy_device(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_device *dev;
+
+	dev = kzalloc_obj(*dev);
+	if (!dev)
+		return ERR_PTR(-ENOMEM);
+
+	btrfs_extent_io_tree_init(fs_info, &dev->alloc_state, 0);
+	INIT_LIST_HEAD(&dev->dev_list);
+	list_add(&dev->dev_list, &fs_info->fs_devices->devices);
+
+	return dev;
+}
+
+static void btrfs_free_dummy_device(struct btrfs_device *dev)
+{
+	btrfs_extent_io_tree_release(&dev->alloc_state);
+	kfree(dev);
+}
+
+struct btrfs_fs_info *btrfs_alloc_dummy_fs_info(u32 nodesize, u32 sectorsize)
+{
+	struct btrfs_fs_info *fs_info = kzalloc_obj(struct btrfs_fs_info);
+
+	if (!fs_info)
+		return fs_info;
+	fs_info->fs_devices = kzalloc_obj(struct btrfs_fs_devices);
+	if (!fs_info->fs_devices) {
+		kfree(fs_info);
+		return NULL;
+	}
+	INIT_LIST_HEAD(&fs_info->fs_devices->devices);
+
+	fs_info->super_copy = kzalloc_obj(struct btrfs_super_block);
+	if (!fs_info->super_copy) {
+		kfree(fs_info->fs_devices);
+		kfree(fs_info);
+		return NULL;
+	}
+
+	btrfs_init_fs_info(fs_info);
+
+	fs_info->nodesize = nodesize;
+	fs_info->sectorsize = sectorsize;
+	fs_info->sectorsize_bits = ilog2(sectorsize);
+
+	/* CRC32C csum size. */
+	fs_info->csum_size = 4;
+	fs_info->csums_per_leaf = BTRFS_MAX_ITEM_SIZE(fs_info) /
+		fs_info->csum_size;
+	fs_info->use_bitmap = btrfs_use_bitmap;
+	set_bit(BTRFS_FS_STATE_DUMMY_FS_INFO, &fs_info->fs_state);
+
+	test_mnt->mnt_sb->s_fs_info = fs_info;
+
+	return fs_info;
+}
+
+void btrfs_free_dummy_fs_info(struct btrfs_fs_info *fs_info)
+{
+	struct btrfs_device *dev, *tmp;
+	struct extent_buffer *eb;
+	unsigned long index;
+
+	if (!fs_info)
+		return;
+
+	if (WARN_ON(!btrfs_is_testing(fs_info)))
+		return;
+
+	test_mnt->mnt_sb->s_fs_info = NULL;
+
+	xa_lock_irq(&fs_info->buffer_tree);
+	xa_for_each(&fs_info->buffer_tree, index, eb) {
+		xa_unlock_irq(&fs_info->buffer_tree);
+		free_extent_buffer(eb);
+		xa_lock_irq(&fs_info->buffer_tree);
+	}
+	xa_unlock_irq(&fs_info->buffer_tree);
+
+	btrfs_mapping_tree_free(fs_info);
+	list_for_each_entry_safe(dev, tmp, &fs_info->fs_devices->devices,
+				 dev_list) {
+		btrfs_free_dummy_device(dev);
+	}
+	btrfs_free_qgroup_config(fs_info);
+	btrfs_free_fs_roots(fs_info);
+	kfree(fs_info->super_copy);
+	btrfs_check_leaked_roots(fs_info);
+	btrfs_extent_buffer_leak_debug_check(fs_info);
+	kfree(fs_info->fs_devices);
+	kfree(fs_info);
+}
+
+void btrfs_free_dummy_root(struct btrfs_root *root)
+{
+	if (IS_ERR_OR_NULL(root))
+		return;
+	/* Will be freed by btrfs_free_fs_roots */
+	if (WARN_ON(test_bit(BTRFS_ROOT_IN_RADIX, &root->state)))
+		return;
+	btrfs_global_root_delete(root);
+	btrfs_put_root(root);
+}
+
+struct btrfs_block_group *
+btrfs_alloc_dummy_block_group(struct btrfs_fs_info *fs_info,
+			      unsigned long length)
+{
+	struct btrfs_block_group *cache;
+
+	cache = kzalloc_obj(*cache);
+	if (!cache)
+		return NULL;
+	cache->free_space_ctl = kzalloc_obj(*cache->free_space_ctl);
+	if (!cache->free_space_ctl) {
+		kfree(cache);
+		return NULL;
+	}
+
+	cache->start = 0;
+	cache->length = length;
+	cache->full_stripe_len = fs_info->sectorsize;
+	cache->fs_info = fs_info;
+
+	INIT_LIST_HEAD(&cache->list);
+	INIT_LIST_HEAD(&cache->cluster_list);
+	INIT_LIST_HEAD(&cache->bg_list);
+	btrfs_init_free_space_ctl(cache, cache->free_space_ctl);
+	mutex_init(&cache->free_space_lock);
+
+	return cache;
+}
+
+void btrfs_free_dummy_block_group(struct btrfs_block_group *cache)
+{
+	if (!cache)
+		return;
+	btrfs_remove_free_space_cache(cache);
+	kfree(cache->free_space_ctl);
+	kfree(cache);
+}
+
+void btrfs_init_dummy_transaction(struct btrfs_transaction *trans, struct btrfs_fs_info *fs_info)
+{
+	memset(trans, 0, sizeof(*trans));
+	trans->fs_info = fs_info;
+	xa_init(&trans->delayed_refs.head_refs);
+	xa_init(&trans->delayed_refs.dirty_extents);
+	spin_lock_init(&trans->delayed_refs.lock);
+}
+
+void btrfs_init_dummy_trans(struct btrfs_trans_handle *trans,
+			    struct btrfs_fs_info *fs_info)
+{
+	memset(trans, 0, sizeof(*trans));
+	trans->transid = 1;
+	trans->type = __TRANS_DUMMY;
+	trans->fs_info = fs_info;
+}
+
+int btrfs_run_sanity_tests(void)
+{
+	int ret, i;
+	u32 sectorsize, nodesize;
+	u32 test_sectorsize[] = {
+		PAGE_SIZE,
+	};
+	ret = btrfs_init_test_fs();
+	if (ret)
+		return ret;
+	for (i = 0; i < ARRAY_SIZE(test_sectorsize); i++) {
+		sectorsize = test_sectorsize[i];
+		for (nodesize = sectorsize;
+		     nodesize <= BTRFS_MAX_METADATA_BLOCKSIZE;
+		     nodesize <<= 1) {
+			pr_info("BTRFS: selftest: sectorsize: %u  nodesize: %u\n",
+				sectorsize, nodesize);
+			ret = btrfs_test_free_space_cache(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_extent_buffer_operations(sectorsize,
+				nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_extent_io(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_inodes(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_qgroups(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_free_space_tree(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_raid_stripe_tree(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_delayed_refs(sectorsize, nodesize);
+			if (ret)
+				goto out;
+			ret = btrfs_test_chunk_allocation(sectorsize, nodesize);
+			if (ret)
+				goto out;
+		}
+	}
+	ret = btrfs_test_extent_map();
+	if (ret)
+		goto out;
+	ret = btrfs_test_zoned();
+
+out:
+	btrfs_destroy_test_fs();
+	return ret;
+}