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, 49 insertions, 0 deletions

diff --git a/include/acpi/pcc.h b/include/acpi/pcc.h
new file mode 100644
index 000000000..840bfc95b
--- /dev/null
+++ b/include/acpi/pcc.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * PCC (Platform Communications Channel) methods
+ */
+
+#ifndef _PCC_H
+#define _PCC_H
+
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+
+struct pcc_mbox_chan {
+	struct mbox_chan *mchan;
+	u64 shmem_base_addr;
+	void __iomem *shmem;
+	u64 shmem_size;
+	u32 latency;
+	u32 max_access_rate;
+	u16 min_turnaround_time;
+};
+
+/* Generic Communications Channel Shared Memory Region */
+#define PCC_SIGNATURE			0x50434300
+/* Generic Communications Channel Command Field */
+#define PCC_CMD_GENERATE_DB_INTR	BIT(15)
+/* Generic Communications Channel Status Field */
+#define PCC_STATUS_CMD_COMPLETE		BIT(0)
+#define PCC_STATUS_SCI_DOORBELL		BIT(1)
+#define PCC_STATUS_ERROR		BIT(2)
+#define PCC_STATUS_PLATFORM_NOTIFY	BIT(3)
+/* Initiator Responder Communications Channel Flags */
+#define PCC_CMD_COMPLETION_NOTIFY	BIT(0)
+
+#define MAX_PCC_SUBSPACES	256
+
+#ifdef CONFIG_PCC
+extern struct pcc_mbox_chan *
+pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id);
+extern void pcc_mbox_free_channel(struct pcc_mbox_chan *chan);
+#else
+static inline struct pcc_mbox_chan *
+pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
+{
+	return ERR_PTR(-ENODEV);
+}
+static inline void pcc_mbox_free_channel(struct pcc_mbox_chan *chan) { }
+#endif
+
+#endif /* _PCC_H */