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, 87 insertions, 0 deletions

diff --git a/drivers/mtd/sm_ftl.h b/drivers/mtd/sm_ftl.h
new file mode 100644
index 000000000..1a1a54ce8
--- /dev/null
+++ b/drivers/mtd/sm_ftl.h
@@ -0,0 +1,87 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright © 2009 - Maxim Levitsky
+ * SmartMedia/xD translation layer
+ *
+ * Based loosly on ssfdc.c which is
+ *  © 2005 Eptar srl
+ *  Author: Claudio Lanconelli <lanconelli.claudio@eptar.com>
+ */
+
+#include <linux/mtd/blktrans.h>
+#include <linux/kfifo.h>
+#include <linux/sched.h>
+#include <linux/completion.h>
+#include <linux/mtd/mtd.h>
+
+
+
+struct ftl_zone {
+	bool initialized;
+	int16_t *lba_to_phys_table;		/* LBA to physical table */
+	struct kfifo free_sectors;	/* queue of free sectors */
+};
+
+struct sm_ftl {
+	struct mtd_blktrans_dev *trans;
+
+	struct mutex mutex;		/* protects the structure */
+	struct ftl_zone *zones;		/* FTL tables for each zone */
+
+	/* Media information */
+	int block_size;			/* block size in bytes */
+	int zone_size;			/* zone size in blocks */
+	int zone_count;			/* number of zones */
+	int max_lba;			/* maximum lba in a zone */
+	int smallpagenand;		/* 256 bytes/page nand */
+	bool readonly;			/* is FS readonly */
+	bool unstable;
+	int cis_block;			/* CIS block location */
+	int cis_boffset;		/* CIS offset in the block */
+	int cis_page_offset;		/* CIS offset in the page */
+
+	/* Cache */
+	int cache_block;		/* block number of cached block */
+	int cache_zone;			/* zone of cached block */
+	unsigned char *cache_data;	/* cached block data */
+	long unsigned int cache_data_invalid_bitmap;
+	bool cache_clean;
+	struct work_struct flush_work;
+	struct timer_list timer;
+
+	/* Geometry stuff */
+	int heads;
+	int sectors;
+	int cylinders;
+
+	struct attribute_group *disk_attributes;
+	u8 cis_buffer[];		/* tmp buffer for cis reads */
+};
+
+struct chs_entry {
+	unsigned long size;
+	unsigned short cyl;
+	unsigned char head;
+	unsigned char sec;
+};
+
+
+#define SM_FTL_PARTN_BITS	3
+
+#define sm_printk(format, ...) \
+	printk(KERN_WARNING "sm_ftl" ": " format "\n", ## __VA_ARGS__)
+
+#define dbg(format, ...) \
+	if (debug) \
+		printk(KERN_DEBUG "sm_ftl" ": " format "\n", ## __VA_ARGS__)
+
+#define dbg_verbose(format, ...) \
+	if (debug > 1) \
+		printk(KERN_DEBUG "sm_ftl" ": " format "\n", ## __VA_ARGS__)
+
+
+static int sm_erase_block(struct sm_ftl *ftl, int zone_num, uint16_t block,
+								int put_free);
+static void sm_mark_block_bad(struct sm_ftl *ftl, int zone_num, int block);
+
+static int sm_recheck_media(struct sm_ftl *ftl);