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, 37 insertions, 0 deletions

diff --git a/include/net/nfc/llc.h b/include/net/nfc/llc.h
new file mode 100644
index 000000000..1f699cb17
--- /dev/null
+++ b/include/net/nfc/llc.h
@@ -0,0 +1,37 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Link Layer Control manager public interface
+ *
+ * Copyright (C) 2012  Intel Corporation. All rights reserved.
+ */
+
+#ifndef __NFC_LLC_H_
+#define __NFC_LLC_H_
+
+#include <net/nfc/hci.h>
+#include <linux/skbuff.h>
+
+#define LLC_NOP_NAME "nop"
+#define LLC_SHDLC_NAME "shdlc"
+
+typedef void (*rcv_to_hci_t) (struct nfc_hci_dev *hdev, struct sk_buff *skb);
+typedef int (*xmit_to_drv_t) (struct nfc_hci_dev *hdev, struct sk_buff *skb);
+typedef void (*llc_failure_t) (struct nfc_hci_dev *hdev, int err);
+
+struct nfc_llc;
+
+struct nfc_llc *nfc_llc_allocate(const char *name, struct nfc_hci_dev *hdev,
+				 xmit_to_drv_t xmit_to_drv,
+				 rcv_to_hci_t rcv_to_hci, int tx_headroom,
+				 int tx_tailroom, llc_failure_t llc_failure);
+void nfc_llc_free(struct nfc_llc *llc);
+
+int nfc_llc_start(struct nfc_llc *llc);
+int nfc_llc_stop(struct nfc_llc *llc);
+void nfc_llc_rcv_from_drv(struct nfc_llc *llc, struct sk_buff *skb);
+int nfc_llc_xmit_from_hci(struct nfc_llc *llc, struct sk_buff *skb);
+
+int nfc_llc_init(void);
+void nfc_llc_exit(void);
+
+#endif /* __NFC_LLC_H_ */