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, 84 insertions, 0 deletions

diff --git a/drivers/scsi/sd_trace.h b/drivers/scsi/sd_trace.h
new file mode 100644
index 000000000..cba3c0b82
--- /dev/null
+++ b/drivers/scsi/sd_trace.h
@@ -0,0 +1,84 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022 Western Digital Corporation or its affiliates.
+ */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM sd
+
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE sd_trace
+
+#if !defined(_SD_TRACE_H) || defined(TRACE_HEADER_MULTI_READ)
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_host.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(scsi_prepare_zone_append,
+
+	    TP_PROTO(struct scsi_cmnd *cmnd, sector_t lba,
+		     unsigned int wp_offset),
+
+	    TP_ARGS(cmnd, lba, wp_offset),
+
+	    TP_STRUCT__entry(
+		     __field( unsigned int, host_no )
+		     __field( unsigned int, channel )
+		     __field( unsigned int, id )
+		     __field( unsigned int, lun )
+		     __field( sector_t,     lba )
+		     __field( unsigned int, wp_offset )
+	    ),
+
+	    TP_fast_assign(
+		__entry->host_no	= cmnd->device->host->host_no;
+		__entry->channel	= cmnd->device->channel;
+		__entry->id		= cmnd->device->id;
+		__entry->lun		= cmnd->device->lun;
+		__entry->lba		= lba;
+		__entry->wp_offset	= wp_offset;
+	    ),
+
+	    TP_printk("host_no=%u, channel=%u id=%u lun=%u lba=%llu wp_offset=%u",
+		      __entry->host_no, __entry->channel, __entry->id,
+		      __entry->lun, __entry->lba, __entry->wp_offset)
+);
+
+TRACE_EVENT(scsi_zone_wp_update,
+
+	    TP_PROTO(struct scsi_cmnd *cmnd, sector_t rq_sector,
+		     unsigned int wp_offset, unsigned int good_bytes),
+
+	    TP_ARGS(cmnd, rq_sector, wp_offset, good_bytes),
+
+	    TP_STRUCT__entry(
+		     __field( unsigned int, host_no )
+		     __field( unsigned int, channel )
+		     __field( unsigned int, id )
+		     __field( unsigned int, lun )
+		     __field( sector_t,     rq_sector )
+		     __field( unsigned int, wp_offset )
+		     __field( unsigned int, good_bytes )
+	    ),
+
+	    TP_fast_assign(
+		__entry->host_no	= cmnd->device->host->host_no;
+		__entry->channel	= cmnd->device->channel;
+		__entry->id		= cmnd->device->id;
+		__entry->lun		= cmnd->device->lun;
+		__entry->rq_sector	= rq_sector;
+		__entry->wp_offset	= wp_offset;
+		__entry->good_bytes	= good_bytes;
+	    ),
+
+	    TP_printk("host_no=%u, channel=%u id=%u lun=%u rq_sector=%llu" \
+		      " wp_offset=%u good_bytes=%u",
+		      __entry->host_no, __entry->channel, __entry->id,
+		      __entry->lun, __entry->rq_sector, __entry->wp_offset,
+		      __entry->good_bytes)
+);
+#endif /* _SD_TRACE_H */
+
+/* This part must be outside protection */
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH ../../drivers/scsi
+#include <trace/define_trace.h>