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, 78 insertions, 0 deletions

diff --git a/samples/rust/rust_soc.rs b/samples/rust/rust_soc.rs
new file mode 100644
index 000000000..f5e5f2f9a
--- /dev/null
+++ b/samples/rust/rust_soc.rs
@@ -0,0 +1,78 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Rust SoC Platform driver sample.
+
+use kernel::{
+    acpi,
+    device::Core,
+    of,
+    platform,
+    prelude::*,
+    soc,
+    str::CString,
+    sync::aref::ARef, //
+};
+use pin_init::pin_init_scope;
+
+#[pin_data]
+struct SampleSocDriver {
+    pdev: ARef<platform::Device>,
+    #[pin]
+    _dev_reg: soc::Registration,
+}
+
+kernel::of_device_table!(
+    OF_TABLE,
+    <SampleSocDriver as platform::Driver>::IdInfo,
+    [(of::DeviceId::new(c"test,rust-device"), ())]
+);
+
+kernel::acpi_device_table!(
+    ACPI_TABLE,
+    <SampleSocDriver as platform::Driver>::IdInfo,
+    [(acpi::DeviceId::new(c"LNUXBEEF"), ())]
+);
+
+impl platform::Driver for SampleSocDriver {
+    type IdInfo = ();
+    type Data<'bound> = Self;
+    const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+    const ACPI_ID_TABLE: Option<acpi::IdTable<Self::IdInfo>> = Some(&ACPI_TABLE);
+
+    fn probe<'bound>(
+        pdev: &'bound platform::Device<Core<'_>>,
+        _info: Option<&'bound Self::IdInfo>,
+    ) -> impl PinInit<Self, Error> + 'bound {
+        dev_dbg!(pdev, "Probe Rust SoC driver sample.\n");
+
+        let pdev = pdev.into();
+        pin_init_scope(move || {
+            let machine = CString::try_from(c"My cool ACME15 dev board")?;
+            let family = CString::try_from(c"ACME")?;
+            let revision = CString::try_from(c"1.2")?;
+            let serial_number = CString::try_from(c"12345")?;
+            let soc_id = CString::try_from(c"ACME15")?;
+
+            let attr = soc::Attributes {
+                machine: Some(machine),
+                family: Some(family),
+                revision: Some(revision),
+                serial_number: Some(serial_number),
+                soc_id: Some(soc_id),
+            };
+
+            Ok(try_pin_init!(SampleSocDriver {
+                pdev: pdev,
+                _dev_reg <- soc::Registration::new(attr),
+            }? Error))
+        })
+    }
+}
+
+kernel::module_platform_driver! {
+    type: SampleSocDriver,
+    name: "rust_soc",
+    authors: ["Matthew Maurer"],
+    description: "Rust SoC Driver",
+    license: "GPL",
+}