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, 55 insertions, 0 deletions

diff --git a/drivers/usb/image/microtek.h b/drivers/usb/image/microtek.h
new file mode 100644
index 000000000..7bd5f4639
--- /dev/null
+++ b/drivers/usb/image/microtek.h
@@ -0,0 +1,55 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+ /*
+ * Driver for Microtek Scanmaker X6 USB scanner and possibly others.
+ * 
+ * (C) Copyright 2000 John Fremlin <vii@penguinpowered.com>
+ * (C) Copyright 2000 Oliver Neukum <Oliver.Neukum@lrz.uni-muenchen.de>
+ *
+ * See microtek.c for history
+ *
+ */
+
+typedef void (*mts_scsi_cmnd_callback)(struct scsi_cmnd *);
+
+
+struct mts_transfer_context
+{
+	struct mts_desc *instance;
+	mts_scsi_cmnd_callback final_callback;
+	struct scsi_cmnd *srb;
+	
+	void *data;
+	unsigned data_length;
+	int data_pipe;
+	struct scatterlist *curr_sg;
+
+	u8 *scsi_status; /* status returned from ep_response after command completion */
+};
+
+
+struct mts_desc {
+	struct mts_desc *next;
+	struct mts_desc *prev;
+
+	struct usb_device *usb_dev;
+	struct usb_interface *usb_intf;
+
+	/* Endpoint addresses */
+	u8 ep_out;
+	u8 ep_response;
+	u8 ep_image;
+
+	struct Scsi_Host *host;
+
+	struct urb *urb;
+	struct mts_transfer_context context;
+};
+
+
+#define MTS_EP_OUT	0x1
+#define MTS_EP_RESPONSE	0x2
+#define MTS_EP_IMAGE	0x3
+#define MTS_EP_TOTAL	0x3
+
+#define MTS_SCSI_ERR_MASK ~0x3fu
+