a73f3ba91f
Add a fuzzer to test the vring handling code against unexpected mutations from the virtio device. After building the sandbox with CONFIG_FUZZ=y, the fuzzer can be invoked with by: UBOOT_SB_FUZZ_TEST=fuzz_vring ./u-boot This fuzzer finds unvalidated inputs in the vring driver that allow a buggy or malicious device to make the driver chase wild pointers. Signed-off-by: Andrew Scull <ascull@google.com>
73 lines
1.9 KiB
C
73 lines
1.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Copyright (c) 2022 Google, Inc.
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* Written by Andrew Scull <ascull@google.com>
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*/
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#include <common.h>
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#include <dm.h>
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#include <virtio.h>
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#include <virtio_ring.h>
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#include <test/fuzz.h>
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static int fuzz_vring(const uint8_t *data, size_t size)
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{
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struct udevice *bus, *dev;
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struct virtio_dev_priv *uc_priv;
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struct virtqueue *vq;
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struct virtio_sg sg[2];
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struct virtio_sg *sgs[2];
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unsigned int len;
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u8 buffer[2][32];
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/* hackily hardcode vring sizes */
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size_t num = 4;
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size_t desc_size = (sizeof(struct vring_desc) * num);
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size_t avail_size = (3 + num) * sizeof(u16);
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size_t used_size = (3 * sizeof(u16)) + (sizeof(struct vring_used_elem) * num);
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if (size < (desc_size + avail_size + used_size))
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return 0;
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/* check probe success */
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if (uclass_first_device(UCLASS_VIRTIO, &bus) || !bus)
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panic("Could not find virtio bus\n");
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/* check the child virtio-rng device is bound */
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if (device_find_first_child(bus, &dev) || !dev)
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panic("Could not find virtio device\n");
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/*
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* fake the virtio device probe by filling in uc_priv->vdev
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* which is used by virtio_find_vqs/virtio_del_vqs.
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*/
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uc_priv = dev_get_uclass_priv(bus);
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uc_priv->vdev = dev;
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/* prepare the scatter-gather buffer */
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sg[0].addr = buffer[0];
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sg[0].length = sizeof(buffer[0]);
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sg[1].addr = buffer[1];
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sg[1].length = sizeof(buffer[1]);
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sgs[0] = &sg[0];
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sgs[1] = &sg[1];
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if (virtio_find_vqs(dev, 1, &vq))
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panic("Could not find vqs\n");
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if (virtqueue_add(vq, sgs, 0, 1))
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panic("Could not add to virtqueue\n");
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/* Simulate device writing to vring */
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memcpy(vq->vring.desc, data, desc_size);
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memcpy(vq->vring.avail, data + desc_size, avail_size);
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memcpy(vq->vring.used, data + desc_size + avail_size, used_size);
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/* Make sure there is a response */
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if (vq->vring.used->idx == 0)
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vq->vring.used->idx = 1;
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virtqueue_get_buf(vq, &len);
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if (virtio_del_vqs(dev))
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panic("Could not delete vqs\n");
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return 0;
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}
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FUZZ_TEST(fuzz_vring, 0);
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