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, 43 insertions, 0 deletions

diff --git a/scripts/Makefile.dtbinst b/scripts/Makefile.dtbinst
new file mode 100644
index 000000000..9d920419a
--- /dev/null
+++ b/scripts/Makefile.dtbinst
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0
+# ==========================================================================
+# Installing dtb files
+#
+# Installs all dtb files listed in $(dtb-y) either in the
+# INSTALL_DTBS_PATH directory or the default location:
+#
+#   $INSTALL_PATH/dtbs/$KERNELRELEASE
+# ==========================================================================
+
+PHONY := __dtbs_install
+__dtbs_install:
+
+include include/config/auto.conf
+include $(srctree)/scripts/Kbuild.include
+
+dst := $(INSTALL_DTBS_PATH)
+
+quiet_cmd_dtb_install = INSTALL $@
+      cmd_dtb_install = install -D -m 0644 $< $@
+
+$(dst)/%: $(obj)/%
+	$(call cmd,dtb_install)
+
+dtbs := $(patsubst $(obj)/%,%,$(call read-file, $(obj)/dtbs-list))
+
+ifdef CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+define gen_install_rules
+$(dst)/%: $(obj)/$(1)%
+	$$(call cmd,dtb_install)
+endef
+
+$(foreach d, $(sort $(dir $(dtbs))), $(eval $(call gen_install_rules,$(d))))
+
+dtbs := $(notdir $(dtbs))
+
+endif # CONFIG_ARCH_WANT_FLAT_DTB_INSTALL
+
+__dtbs_install: $(addprefix $(dst)/, $(dtbs))
+	@:
+
+.PHONY: $(PHONY)