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, 75 insertions, 0 deletions

diff --git a/scripts/headers_install.sh b/scripts/headers_install.sh
new file mode 100755
index 000000000..2f1d1767c
--- /dev/null
+++ b/scripts/headers_install.sh
@@ -0,0 +1,75 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+if [ $# -ne 2 ]
+then
+	echo "Usage: headers_install.sh INFILE OUTFILE"
+	echo
+	echo "Prepares kernel header files for use by user space, by removing"
+	echo "all compiler.h definitions and #includes, removing any"
+	echo "#ifdef __KERNEL__ sections, and putting __underscores__ around"
+	echo "asm/inline/volatile keywords."
+	echo
+	echo "INFILE: header file to operate on"
+	echo "OUTFILE: output file which the processed header is written to"
+
+	exit 1
+fi
+
+# Grab arguments
+INFILE=$1
+OUTFILE=$2
+TMPFILE=$OUTFILE.tmp
+
+trap 'rm -f $OUTFILE $TMPFILE' EXIT
+
+# SPDX-License-Identifier with GPL variants must have "WITH Linux-syscall-note"
+if [ -n "$(sed -n -e "/SPDX-License-Identifier:.*GPL-/{/WITH Linux-syscall-note/!p}" $INFILE)" ]; then
+	echo "error: $INFILE: missing \"WITH Linux-syscall-note\" for SPDX-License-Identifier" >&2
+	exit 1
+fi
+
+sed -E -e '
+	s/([[:space:](])(__user|__force|__iomem)[[:space:]]/\1/g
+	s/__attribute_const__([[:space:]]|$)/\1/g
+	s@^#include <linux/compiler.h>@@
+	s/(^|[^a-zA-Z0-9])__packed([^a-zA-Z0-9_]|$)/\1__attribute__((packed))\2/g
+	s/(^|[[:space:](])(inline|asm|volatile)([[:space:](]|$)/\1__\2__\3/g
+	s@#(ifndef|define|endif[[:space:]]*/[*])[[:space:]]*_UAPI@#\1 @
+	s/__ASSEMBLY__/__ASSEMBLER__/g
+' $INFILE > $TMPFILE || exit 1
+
+scripts/unifdef -U__KERNEL__ -D__EXPORTED_HEADERS__ $TMPFILE > $OUTFILE
+[ $? -gt 1 ] && exit 1
+
+# Remove /* ... */ style comments, and find CONFIG_ references in code
+configs=$(sed -e '
+:comment
+	s:/\*[^*][^*]*:/*:
+	s:/\*\*\**\([^/]\):/*\1:
+	t comment
+	s:/\*\*/: :
+	t comment
+	/\/\*/! b check
+	N
+	b comment
+:print
+	P
+	D
+:check
+	s:^\(CONFIG_[[:alnum:]_]*\):\1\n:
+	t print
+	s:^[[:alnum:]_][[:alnum:]_]*::
+	s:^[^[:alnum:]_][^[:alnum:]_]*::
+	t check
+	d
+' $OUTFILE)
+
+for c in $configs
+do
+	echo "error: $INFILE: leak $c to user-space" >&2
+	exit 1
+done
+
+rm -f $TMPFILE
+trap - EXIT