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, 45 insertions, 0 deletions

diff --git a/Documentation/driver-api/tty/console.rst b/Documentation/driver-api/tty/console.rst
new file mode 100644
index 000000000..4348e36cd
--- /dev/null
+++ b/Documentation/driver-api/tty/console.rst
@@ -0,0 +1,45 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=======
+Console
+=======
+
+.. contents:: :local:
+
+Struct Console
+==============
+
+.. kernel-doc:: include/linux/console.h
+   :identifiers: console cons_flags
+
+Internals
+---------
+
+.. kernel-doc:: include/linux/console.h
+   :identifiers: nbcon_state nbcon_prio nbcon_context nbcon_write_context
+
+Struct Consw
+============
+
+.. kernel-doc:: include/linux/console.h
+   :identifiers: consw
+
+Console functions
+=================
+
+.. kernel-doc:: include/linux/console.h
+   :identifiers: console_srcu_read_flags console_srcu_write_flags
+        console_is_registered for_each_console_srcu for_each_console
+
+.. kernel-doc:: drivers/tty/vt/selection.c
+   :export:
+.. kernel-doc:: drivers/tty/vt/vt.c
+   :export:
+
+Internals
+---------
+
+.. kernel-doc:: drivers/tty/vt/selection.c
+   :internal:
+.. kernel-doc:: drivers/tty/vt/vt.c
+   :internal: