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, 69 insertions, 0 deletions

diff --git a/scripts/Makefile b/scripts/Makefile
new file mode 100644
index 000000000..3434a82a1
--- /dev/null
+++ b/scripts/Makefile
@@ -0,0 +1,69 @@
+# SPDX-License-Identifier: GPL-2.0
+###
+# scripts contains sources for various helper programs used throughout
+# the kernel for the build process.
+
+hostprogs-always-$(CONFIG_KALLSYMS)			+= kallsyms
+hostprogs-always-$(BUILD_C_RECORDMCOUNT)		+= recordmcount
+hostprogs-always-$(CONFIG_BUILDTIME_TABLE_SORT)		+= sorttable
+hostprogs-always-$(CONFIG_ASN1)				+= asn1_compiler
+hostprogs-always-$(CONFIG_MODULE_SIG_FORMAT)		+= sign-file
+hostprogs-always-$(CONFIG_SYSTEM_EXTRA_CERTIFICATE)	+= insert-sys-cert
+hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)		+= rustdoc_test_builder
+hostprogs-always-$(CONFIG_RUST_KERNEL_DOCTESTS)		+= rustdoc_test_gen
+hostprogs-always-$(CONFIG_TRACEPOINTS)			+= tracepoint-update
+
+sorttable-objs := sorttable.o elf-parse.o
+tracepoint-update-objs := tracepoint-update.o elf-parse.o
+
+ifneq ($(or $(CONFIG_X86_64),$(CONFIG_X86_32)),)
+always-$(CONFIG_RUST)					+= target.json
+filechk_rust_target = $< < include/config/auto.conf
+
+$(obj)/target.json: scripts/generate_rust_target include/config/auto.conf FORCE
+	$(call filechk,rust_target)
+endif
+
+hostprogs += generate_rust_target
+generate_rust_target-rust := y
+rustdoc_test_builder-rust := y
+rustdoc_test_gen-rust := y
+
+HOSTCFLAGS_tracepoint-update.o = -I$(srctree)/tools/include
+HOSTCFLAGS_elf-parse.o = -I$(srctree)/tools/include
+HOSTCFLAGS_sorttable.o = -I$(srctree)/tools/include
+HOSTLDLIBS_sorttable = -lpthread
+HOSTCFLAGS_asn1_compiler.o = -I$(srctree)/include
+HOSTCFLAGS_sign-file.o = $(shell $(HOSTPKG_CONFIG) --cflags libcrypto 2> /dev/null)
+HOSTCFLAGS_sign-file.o += -I$(srctree)/tools/include/uapi/
+HOSTLDLIBS_sign-file = $(shell $(HOSTPKG_CONFIG) --libs libcrypto 2> /dev/null || echo -lcrypto)
+
+ifdef CONFIG_UNWINDER_ORC
+ifeq ($(ARCH),x86_64)
+SRCARCH := x86
+endif
+ifeq ($(ARCH),loongarch)
+SRCARCH := loongarch
+endif
+HOSTCFLAGS_sorttable.o += -I$(srctree)/tools/arch/$(SRCARCH)/include
+HOSTCFLAGS_sorttable.o += -DUNWINDER_ORC_ENABLED
+endif
+
+ifdef CONFIG_BUILDTIME_MCOUNT_SORT
+HOSTCFLAGS_sorttable.o += -DMCOUNT_SORT_ENABLED
+endif
+
+# The following programs are only built on demand
+hostprogs += unifdef gen_packed_field_checks
+
+# The module linker script is preprocessed on demand
+targets += module.lds
+
+subdir-$(CONFIG_GCC_PLUGINS) += gcc-plugins
+subdir-$(CONFIG_GENKSYMS) += genksyms
+subdir-$(CONFIG_GENDWARFKSYMS) += gendwarfksyms
+subdir-$(CONFIG_SECURITY_SELINUX) += selinux
+subdir-$(CONFIG_SECURITY_IPE) += ipe
+
+# Let clean descend into subdirs
+subdir-	+= basic dtc gdb kconfig mod