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, 38 insertions, 0 deletions

diff --git a/include/video/maxinefb.h b/include/video/maxinefb.h
new file mode 100644
index 000000000..2b66b32f3
--- /dev/null
+++ b/include/video/maxinefb.h
@@ -0,0 +1,38 @@
+/*
+ *      linux/drivers/video/maxinefb.h
+ *
+ *      DECstation 5000/xx onboard framebuffer support, Copyright (C) 1999 by
+ *      Michael Engel <engel@unix-ag.org> and Karsten Merker <merker@guug.de>
+ *      This file is subject to the terms and conditions of the GNU General
+ *      Public License.  See the file COPYING in the main directory of this
+ *      archive for more details.
+ */
+
+#include <asm/addrspace.h>
+
+/*
+ * IMS332 video controller register base address
+ */
+#define MAXINEFB_IMS332_ADDRESS		CKSEG1ADDR(0x1c140000)
+
+/*
+ * Begin of DECstation 5000/xx onboard framebuffer memory, default resolution
+ * is 1024x768x8
+ */
+#define DS5000_xx_ONBOARD_FBMEM_START	CKSEG1ADDR(0x0a000000)
+
+/*
+ *      The IMS 332 video controller used in the DECstation 5000/xx series
+ *      uses 32 bits wide registers; the following defines declare the
+ *      register numbers, to get the real offset, these have to be multiplied
+ *      by four.
+ */
+
+#define IMS332_REG_CURSOR_RAM           0x200	/* hardware cursor bitmap */
+
+/*
+ * The color palette entries have the form 0x00BBGGRR
+ */
+#define IMS332_REG_COLOR_PALETTE        0x100	/* color palette, 256 entries */
+#define IMS332_REG_CURSOR_COLOR_PALETTE	0x0a1	/* cursor color palette, */
+						/* 3 entries             */