From 33a154a96e71a34a1bcca9f40da343dbbf7b38b4 Mon Sep 17 00:00:00 2001
From: Alexei Starovoitov <ast@kernel.org>
Date: Thu, 1 Oct 2026 14:52:55 +0000
Subject: selftests/bpf: Test packet range of pointers sharing an id

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 scripts/syscallhdr.sh | 98 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 98 insertions(+)
 create mode 100755 scripts/syscallhdr.sh

(limited to 'scripts/syscallhdr.sh')

diff --git a/scripts/syscallhdr.sh b/scripts/syscallhdr.sh
new file mode 100755
index 000000000..22e34cd46
--- /dev/null
+++ b/scripts/syscallhdr.sh
@@ -0,0 +1,98 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Generate a syscall number header.
+#
+# Each line of the syscall table should have the following format:
+#
+# NR ABI NAME [NATIVE] [COMPAT]
+#
+# NR       syscall number
+# ABI      ABI name
+# NAME     syscall name
+# NATIVE   native entry point (optional)
+# COMPAT   compat entry point (optional)
+
+set -e
+
+usage() {
+	echo >&2 "usage: $0 [--abis ABIS] [--emit-nr] [--offset OFFSET] [--prefix PREFIX] INFILE OUTFILE" >&2
+	echo >&2
+	echo >&2 "  INFILE    input syscall table"
+	echo >&2 "  OUTFILE   output header file"
+	echo >&2
+	echo >&2 "options:"
+	echo >&2 "  --abis ABIS        ABI(s) to handle (By default, all lines are handled)"
+	echo >&2 "  --emit-nr          Emit the macro of the number of syscalls (__NR_syscalls)"
+	echo >&2 "  --offset OFFSET    The offset of syscall numbers"
+	echo >&2 "  --prefix PREFIX    The prefix to the macro like __NR_<PREFIX><NAME>"
+	exit 1
+}
+
+# default unless specified by options
+abis=
+emit_nr=
+offset=
+prefix=
+
+while [ $# -gt 0 ]
+do
+	case $1 in
+	--abis)
+		abis=$(echo "($2)" | tr ',' '|')
+		shift 2;;
+	--emit-nr)
+		emit_nr=1
+		shift 1;;
+	--offset)
+		offset=$2
+		shift 2;;
+	--prefix)
+		prefix=$2
+		shift 2;;
+	-*)
+		echo "$1: unknown option" >&2
+		usage;;
+	*)
+		break;;
+	esac
+done
+
+if [ $# -ne 2 ]; then
+	usage
+fi
+
+infile="$1"
+outfile="$2"
+
+guard=_UAPI_ASM_$(basename "$outfile" |
+	sed -e 'y/abcdefghijklmnopqrstuvwxyz/ABCDEFGHIJKLMNOPQRSTUVWXYZ/' \
+	-e 's/[^A-Z0-9_]/_/g' -e 's/__/_/g')
+
+grep -E "^[0-9A-Fa-fXx]+[[:space:]]+$abis" "$infile" | {
+	echo "#ifndef $guard"
+	echo "#define $guard"
+	echo
+
+	max=0
+	while read nr abi name native compat ; do
+
+		max=$nr
+
+		if [ -n "$offset" ]; then
+			nr="($offset + $nr)"
+		fi
+
+		echo "#define __NR_$prefix$name $nr"
+	done
+
+	if [ -n "$emit_nr" ]; then
+		echo
+		echo "#ifdef __KERNEL__"
+		echo "#define __NR_${prefix}syscalls $(($max + 1))"
+		echo "#endif"
+	fi
+
+	echo
+	echo "#endif /* $guard */"
+} > "$outfile"
-- 
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