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, 85 insertions, 0 deletions

diff --git a/usr/Makefile b/usr/Makefile
new file mode 100644
index 000000000..e8f42478a
--- /dev/null
+++ b/usr/Makefile
@@ -0,0 +1,85 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# kbuild file for usr/ - including initramfs image
+#
+
+compress-y					:= copy
+compress-$(CONFIG_INITRAMFS_COMPRESSION_GZIP)	:= gzip
+compress-$(CONFIG_INITRAMFS_COMPRESSION_BZIP2)	:= bzip2
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZMA)	:= lzma
+compress-$(CONFIG_INITRAMFS_COMPRESSION_XZ)	:= xzmisc
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZO)	:= lzo
+compress-$(CONFIG_INITRAMFS_COMPRESSION_LZ4)	:= lz4
+compress-$(CONFIG_INITRAMFS_COMPRESSION_ZSTD)	:= zstd
+
+obj-$(CONFIG_BLK_DEV_INITRD) := initramfs_data.o
+
+$(obj)/initramfs_data.o: $(obj)/initramfs_inc_data
+
+hostprogs := gen_init_cpio
+
+ramfs-input := $(CONFIG_INITRAMFS_SOURCE)
+cpio-data :=
+
+# If CONFIG_INITRAMFS_SOURCE is empty, generate a small initramfs with the
+# default contents.
+ifeq ($(ramfs-input),)
+ramfs-input := $(src)/default_cpio_list
+endif
+
+ifeq ($(words $(ramfs-input)),1)
+
+# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
+# .cpio, use it directly as an initramfs.
+ifneq ($(filter %.cpio,$(ramfs-input)),)
+cpio-data := $(ramfs-input)
+endif
+
+# If CONFIG_INITRAMFS_SOURCE specifies a single file, and it is suffixed with
+# .cpio.*, use it directly as an initramfs, and avoid double compression.
+ifeq ($(words $(subst .cpio.,$(space),$(ramfs-input))),2)
+cpio-data := $(ramfs-input)
+compress-y := copy
+endif
+
+endif
+
+# For other cases, generate the initramfs cpio archive based on the contents
+# specified by CONFIG_INITRAMFS_SOURCE.
+ifeq ($(cpio-data),)
+
+cpio-data := $(obj)/initramfs_data.cpio
+
+# .initramfs_data.cpio.d is used to identify all files included
+# in initramfs and to detect if any files are added/removed.
+# Removed files are identified by directory timestamp being updated
+# The dependency list is generated by gen_initramfs.sh -l
+-include $(obj)/.initramfs_data.cpio.d
+
+# do not try to update files included in initramfs
+$(deps_initramfs): ;
+
+quiet_cmd_initfs = GEN     $@
+      cmd_initfs = \
+	$(CONFIG_SHELL) $< -o $@ -l $(obj)/.initramfs_data.cpio.d \
+	$(addprefix -u , $(CONFIG_INITRAMFS_ROOT_UID)) \
+	$(addprefix -g , $(CONFIG_INITRAMFS_ROOT_GID)) \
+	$(if $(KBUILD_BUILD_TIMESTAMP), -d "$(KBUILD_BUILD_TIMESTAMP)") \
+	$(ramfs-input)
+
+# We rebuild initramfs_data.cpio if:
+# 1) Any included file is newer than initramfs_data.cpio
+# 2) There are changes in which files are included (added or deleted)
+# 3) If gen_init_cpio are newer than initramfs_data.cpio
+# 4) Arguments to gen_initramfs.sh changes
+$(obj)/initramfs_data.cpio: $(src)/gen_initramfs.sh $(obj)/gen_init_cpio $(deps_initramfs) FORCE
+	$(call if_changed,initfs)
+
+endif
+
+$(obj)/initramfs_inc_data: $(cpio-data) FORCE
+	$(call if_changed,$(compress-y))
+
+targets += initramfs_data.cpio initramfs_inc_data
+
+subdir-$(CONFIG_UAPI_HEADER_TEST) += include