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, 40 insertions, 0 deletions

diff --git a/include/uapi/asm-generic/int-ll64.h b/include/uapi/asm-generic/int-ll64.h
new file mode 100644
index 000000000..1ed069642
--- /dev/null
+++ b/include/uapi/asm-generic/int-ll64.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * asm-generic/int-ll64.h
+ *
+ * Integer declarations for architectures which use "long long"
+ * for 64-bit types.
+ */
+
+#ifndef _UAPI_ASM_GENERIC_INT_LL64_H
+#define _UAPI_ASM_GENERIC_INT_LL64_H
+
+#include <asm/bitsperlong.h>
+
+#ifndef __ASSEMBLY__
+/*
+ * __xx is ok: it doesn't pollute the POSIX namespace. Use these in the
+ * header files exported to user space
+ */
+
+typedef __signed__ char __s8;
+typedef unsigned char __u8;
+
+typedef __signed__ short __s16;
+typedef unsigned short __u16;
+
+typedef __signed__ int __s32;
+typedef unsigned int __u32;
+
+#ifdef __GNUC__
+__extension__ typedef __signed__ long long __s64;
+__extension__ typedef unsigned long long __u64;
+#else
+typedef __signed__ long long __s64;
+typedef unsigned long long __u64;
+#endif
+
+#endif /* __ASSEMBLY__ */
+
+
+#endif /* _UAPI_ASM_GENERIC_INT_LL64_H */