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, 62 insertions, 0 deletions

diff --git a/init/Makefile b/init/Makefile
new file mode 100644
index 000000000..d6f75d890
--- /dev/null
+++ b/init/Makefile
@@ -0,0 +1,62 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for the linux kernel.
+#
+
+ccflags-y := -fno-function-sections -fno-data-sections
+
+obj-y                          := main.o version.o mounts.o
+ifneq ($(CONFIG_BLK_DEV_INITRD),y)
+obj-y                          += noinitramfs.o
+else
+obj-$(CONFIG_BLK_DEV_INITRD)   += initramfs.o
+endif
+obj-$(CONFIG_GENERIC_CALIBRATE_DELAY) += calibrate.o
+obj-$(CONFIG_INITRAMFS_TEST)   += initramfs_test.o
+
+obj-y                          += init_task.o
+
+mounts-y			:= do_mounts.o
+mounts-$(CONFIG_BLK_DEV_RAM)	+= do_mounts_rd.o
+mounts-$(CONFIG_BLK_DEV_INITRD)	+= do_mounts_initrd.o
+
+#
+# UTS_VERSION
+#
+
+smp-flag-$(CONFIG_SMP)			:= SMP
+preempt-flag-$(CONFIG_PREEMPT_BUILD)	:= PREEMPT
+preempt-flag-$(CONFIG_PREEMPT_DYNAMIC)	:= PREEMPT_DYNAMIC
+preempt-flag-$(CONFIG_PREEMPT_RT)	:= PREEMPT_RT
+
+build-version = $(or $(KBUILD_BUILD_VERSION), $(build-version-auto))
+build-timestamp = $(or $(KBUILD_BUILD_TIMESTAMP), $(build-timestamp-auto))
+
+# Maximum length of UTS_VERSION is 64 chars
+filechk_uts_version = \
+	utsver=$$(echo '$(pound)'"$(build-version)" $(smp-flag-y) $(preempt-flag-y) "$(build-timestamp)" | cut -b -64); \
+	echo '$(pound)'define UTS_VERSION \""$${utsver}"\"
+
+#
+# Build version.c with temporary UTS_VERSION
+#
+
+$(obj)/utsversion-tmp.h: FORCE
+	$(call filechk,uts_version)
+
+clean-files += utsversion-tmp.h
+
+$(obj)/version.o: $(obj)/utsversion-tmp.h
+CFLAGS_version.o := -include $(obj)/utsversion-tmp.h
+
+#
+# Build version-timestamp.c with final UTS_VERSION
+#
+
+include/generated/utsversion.h: build-version-auto = $(shell $(srctree)/scripts/build-version)
+include/generated/utsversion.h: build-timestamp-auto = $(shell LC_ALL=C date)
+include/generated/utsversion.h: FORCE
+	$(call filechk,uts_version)
+
+$(obj)/version-timestamp.o: include/generated/utsversion.h
+CFLAGS_version-timestamp.o := -include include/generated/utsversion.h