selftests/bpf: Test packet range of pointers sharing an idgrafted

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>

1 files changed, 44 insertions, 0 deletions

diff --git a/scripts/install.sh b/scripts/install.sh
new file mode 100755
index 000000000..05d62ac51
--- /dev/null
+++ b/scripts/install.sh
@@ -0,0 +1,44 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Copyright (C) 1995 by Linus Torvalds
+#
+# Adapted from code in arch/i386/boot/Makefile by H. Peter Anvin
+# Common code factored out by Masahiro Yamada
+
+set -e
+
+# Make sure the files actually exist
+for file in "${KBUILD_IMAGE}" System.map
+do
+	if [ ! -f "${file}" ]; then
+		echo >&2
+		echo >&2 " *** Missing file: ${file}"
+		echo >&2 ' *** You need to run "make" before "make install".'
+		echo >&2
+		exit 1
+	fi
+done
+
+if [ -n "${INSTALL_PATH}" ] && ! [ -e "${INSTALL_PATH}" ]; then
+	mkdir -p "${INSTALL_PATH}"
+fi
+
+# User/arch may have a custom install script
+for file in "${HOME}/bin/${INSTALLKERNEL}"		\
+	    "/sbin/${INSTALLKERNEL}"			\
+	    "${srctree}/arch/${SRCARCH}/install.sh"	\
+	    "${srctree}/arch/${SRCARCH}/boot/install.sh"
+do
+	if [ ! -x "${file}" ]; then
+		continue
+	fi
+
+	# installkernel(8) says the parameters are like follows:
+	#
+	#   installkernel version zImage System.map [directory]
+	exec "${file}" "${KERNELRELEASE}" "${KBUILD_IMAGE}" System.map "${INSTALL_PATH}"
+done
+
+echo "No install script found" >&2
+exit 1