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, 64 insertions, 0 deletions

diff --git a/drivers/vfio/cdx/private.h b/drivers/vfio/cdx/private.h
new file mode 100644
index 000000000..4c00bf633
--- /dev/null
+++ b/drivers/vfio/cdx/private.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2022-2023, Advanced Micro Devices, Inc.
+ */
+
+#ifndef VFIO_CDX_PRIVATE_H
+#define VFIO_CDX_PRIVATE_H
+
+#include <linux/mutex.h>
+
+#define VFIO_CDX_OFFSET_SHIFT    40
+
+static inline u64 vfio_cdx_index_to_offset(u32 index)
+{
+	return ((u64)(index) << VFIO_CDX_OFFSET_SHIFT);
+}
+
+struct vfio_cdx_irq {
+	u32			flags;
+	u32			count;
+	int			irq_no;
+	struct eventfd_ctx	*trigger;
+	char			*name;
+};
+
+struct vfio_cdx_region {
+	u32			flags;
+	u32			type;
+	u64			addr;
+	resource_size_t		size;
+};
+
+struct vfio_cdx_device {
+	struct vfio_device	vdev;
+	struct vfio_cdx_region	*regions;
+	struct mutex		cdx_irqs_lock;
+	struct vfio_cdx_irq	*cdx_irqs;
+	u32			flags;
+#define BME_SUPPORT BIT(0)
+	u32			msi_count;
+};
+
+#ifdef CONFIG_GENERIC_MSI_IRQ
+int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
+			    u32 flags, unsigned int index,
+			    unsigned int start, unsigned int count,
+			    void *data);
+
+void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev);
+#else
+static int vfio_cdx_set_irqs_ioctl(struct vfio_cdx_device *vdev,
+				   u32 flags, unsigned int index,
+				   unsigned int start, unsigned int count,
+				   void *data)
+{
+	return -EINVAL;
+}
+
+static void vfio_cdx_irqs_cleanup(struct vfio_cdx_device *vdev)
+{
+}
+#endif
+
+#endif /* VFIO_CDX_PRIVATE_H */