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, 93 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/signal.h b/include/uapi/asm-generic/signal.h
new file mode 100644
index 000000000..0eb69dc8e
--- /dev/null
+++ b/include/uapi/asm-generic/signal.h
@@ -0,0 +1,93 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef _UAPI__ASM_GENERIC_SIGNAL_H
+#define _UAPI__ASM_GENERIC_SIGNAL_H
+
+#include <linux/types.h>
+
+#define _NSIG		64
+#define _NSIG_BPW	__BITS_PER_LONG
+#define _NSIG_WORDS	(_NSIG / _NSIG_BPW)
+
+#define SIGHUP		 1
+#define SIGINT		 2
+#define SIGQUIT		 3
+#define SIGILL		 4
+#define SIGTRAP		 5
+#define SIGABRT		 6
+#define SIGIOT		 6
+#define SIGBUS		 7
+#define SIGFPE		 8
+#define SIGKILL		 9
+#define SIGUSR1		10
+#define SIGSEGV		11
+#define SIGUSR2		12
+#define SIGPIPE		13
+#define SIGALRM		14
+#define SIGTERM		15
+#define SIGSTKFLT	16
+#define SIGCHLD		17
+#define SIGCONT		18
+#define SIGSTOP		19
+#define SIGTSTP		20
+#define SIGTTIN		21
+#define SIGTTOU		22
+#define SIGURG		23
+#define SIGXCPU		24
+#define SIGXFSZ		25
+#define SIGVTALRM	26
+#define SIGPROF		27
+#define SIGWINCH	28
+#define SIGIO		29
+#define SIGPOLL		SIGIO
+/*
+#define SIGLOST		29
+*/
+#define SIGPWR		30
+#define SIGSYS		31
+#define	SIGUNUSED	31
+
+/* These should not be considered constants from userland.  */
+#define SIGRTMIN	32
+#ifndef SIGRTMAX
+#define SIGRTMAX	_NSIG
+#endif
+
+#if !defined MINSIGSTKSZ || !defined SIGSTKSZ
+#define MINSIGSTKSZ	2048
+#define SIGSTKSZ	8192
+#endif
+
+#ifndef __ASSEMBLY__
+typedef struct {
+	unsigned long sig[_NSIG_WORDS];
+} sigset_t;
+
+/* not actually used, but required for linux/syscalls.h */
+typedef unsigned long old_sigset_t;
+
+#include <asm-generic/signal-defs.h>
+
+#ifdef SA_RESTORER
+#define __ARCH_HAS_SA_RESTORER
+#endif
+
+#ifndef __KERNEL__
+struct sigaction {
+	__sighandler_t sa_handler;
+	unsigned long sa_flags;
+#ifdef SA_RESTORER
+	__sigrestore_t sa_restorer;
+#endif
+	sigset_t sa_mask;		/* mask last for extensibility */
+};
+#endif
+
+typedef struct sigaltstack {
+	void __user *ss_sp;
+	int ss_flags;
+	__kernel_size_t ss_size;
+} stack_t;
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* _UAPI__ASM_GENERIC_SIGNAL_H */