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, 100 insertions, 0 deletions

diff --git a/drivers/md/dm-vdo/logger.h b/drivers/md/dm-vdo/logger.h
new file mode 100644
index 000000000..ae6ad691c
--- /dev/null
+++ b/drivers/md/dm-vdo/logger.h
@@ -0,0 +1,100 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef VDO_LOGGER_H
+#define VDO_LOGGER_H
+
+#include <linux/kern_levels.h>
+#include <linux/module.h>
+#include <linux/ratelimit.h>
+#include <linux/device-mapper.h>
+
+/* Custom logging utilities for UDS */
+
+enum {
+	VDO_LOG_EMERG = LOGLEVEL_EMERG,
+	VDO_LOG_ALERT = LOGLEVEL_ALERT,
+	VDO_LOG_CRIT = LOGLEVEL_CRIT,
+	VDO_LOG_ERR = LOGLEVEL_ERR,
+	VDO_LOG_WARNING = LOGLEVEL_WARNING,
+	VDO_LOG_NOTICE = LOGLEVEL_NOTICE,
+	VDO_LOG_INFO = LOGLEVEL_INFO,
+	VDO_LOG_DEBUG = LOGLEVEL_DEBUG,
+
+	VDO_LOG_MAX = VDO_LOG_DEBUG,
+	VDO_LOG_DEFAULT = VDO_LOG_INFO,
+};
+
+extern int vdo_log_level;
+
+#define DM_MSG_PREFIX "vdo"
+#define VDO_LOGGING_MODULE_NAME DM_NAME ": " DM_MSG_PREFIX
+
+/* Apply a rate limiter to a log method call. */
+#define vdo_log_ratelimit(log_fn, ...)                                    \
+	do {                                                              \
+		static DEFINE_RATELIMIT_STATE(_rs,                        \
+					      DEFAULT_RATELIMIT_INTERVAL, \
+					      DEFAULT_RATELIMIT_BURST);   \
+		if (__ratelimit(&_rs)) {                                  \
+			log_fn(__VA_ARGS__);                              \
+		}                                                         \
+	} while (0)
+
+int vdo_get_log_level(void);
+
+void vdo_log_embedded_message(int priority, const char *module, const char *prefix,
+			      const char *fmt1, va_list args1, const char *fmt2, ...)
+	__printf(4, 0) __printf(6, 7);
+
+void vdo_log_backtrace(int priority);
+
+/* All log functions will preserve the caller's value of errno. */
+
+#define vdo_log_strerror(priority, errnum, ...) \
+	__vdo_log_strerror(priority, errnum, VDO_LOGGING_MODULE_NAME, __VA_ARGS__)
+
+int __vdo_log_strerror(int priority, int errnum, const char *module,
+		       const char *format, ...)
+	__printf(4, 5);
+
+int vdo_vlog_strerror(int priority, int errnum, const char *module, const char *format,
+		      va_list args)
+	__printf(4, 0);
+
+/* Log an error prefixed with the string associated with the errnum. */
+#define vdo_log_error_strerror(errnum, ...) \
+	vdo_log_strerror(VDO_LOG_ERR, errnum, __VA_ARGS__)
+
+#define vdo_log_debug_strerror(errnum, ...) \
+	vdo_log_strerror(VDO_LOG_DEBUG, errnum, __VA_ARGS__)
+
+#define vdo_log_info_strerror(errnum, ...) \
+	vdo_log_strerror(VDO_LOG_INFO, errnum, __VA_ARGS__)
+
+#define vdo_log_warning_strerror(errnum, ...) \
+	vdo_log_strerror(VDO_LOG_WARNING, errnum, __VA_ARGS__)
+
+#define vdo_log_fatal_strerror(errnum, ...) \
+	vdo_log_strerror(VDO_LOG_CRIT, errnum, __VA_ARGS__)
+
+#define vdo_log_message(priority, ...) \
+	__vdo_log_message(priority, VDO_LOGGING_MODULE_NAME, __VA_ARGS__)
+
+void __vdo_log_message(int priority, const char *module, const char *format, ...)
+	__printf(3, 4);
+
+#define vdo_log_debug(...) vdo_log_message(VDO_LOG_DEBUG, __VA_ARGS__)
+
+#define vdo_log_info(...) vdo_log_message(VDO_LOG_INFO, __VA_ARGS__)
+
+#define vdo_log_warning(...) vdo_log_message(VDO_LOG_WARNING, __VA_ARGS__)
+
+#define vdo_log_error(...) vdo_log_message(VDO_LOG_ERR, __VA_ARGS__)
+
+#define vdo_log_fatal(...) vdo_log_message(VDO_LOG_CRIT, __VA_ARGS__)
+
+void vdo_pause_for_logger(void);
+#endif /* VDO_LOGGER_H */