CVE-2021-47561 i2c: virtio: disable timeout handling

2024-05-2415:12:50

Linux

www.cve.org

linux kernel

i2c virtio

timeout handling

vulnerability

memory corruption

guest bus

rust-vmm

vhost-device

6.4 Medium

AI Score

Confidence

Low

0.0004 Low

EPSS

Percentile

9.1%

JSON

In the Linux kernel, the following vulnerability has been resolved:

i2c: virtio: disable timeout handling

If a timeout is hit, it can result is incorrect data on the I2C bus
and/or memory corruptions in the guest since the device can still be
operating on the buffers it was given while the guest has freed them.

Here is, for example, the start of a slub_debug splat which was
triggered on the next transfer after one transfer was forced to timeout
by setting a breakpoint in the backend (rust-vmm/vhost-device):

BUG kmalloc-1k (Not tainted): Poison overwritten
First byte 0x1 instead of 0x6b
Allocated in virtio_i2c_xfer+0x65/0x35c age=350 cpu=0 pid=29
__kmalloc+0xc2/0x1c9
virtio_i2c_xfer+0x65/0x35c
__i2c_transfer+0x429/0x57d
i2c_transfer+0x115/0x134
i2cdev_ioctl_rdwr+0x16a/0x1de
i2cdev_ioctl+0x247/0x2ed
vfs_ioctl+0x21/0x30
sys_ioctl+0xb18/0xb41
Freed in virtio_i2c_xfer+0x32e/0x35c age=244 cpu=0 pid=29
kfree+0x1bd/0x1cc
virtio_i2c_xfer+0x32e/0x35c
__i2c_transfer+0x429/0x57d
i2c_transfer+0x115/0x134
i2cdev_ioctl_rdwr+0x16a/0x1de
i2cdev_ioctl+0x247/0x2ed
vfs_ioctl+0x21/0x30
sys_ioctl+0xb18/0xb41

There is no simple fix for this (the driver would have to always create
bounce buffers and hold on to them until the device eventually returns
the buffers), so just disable the timeout support for now.

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/i2c/busses/i2c-virtio.c"
    ],
    "versions": [
      {
        "version": "3cfc88380413",
        "lessThan": "cc432b0727ce",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "3cfc88380413",
        "lessThan": "84e1d0bf1d71",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/i2c/busses/i2c-virtio.c"
    ],
    "versions": [
      {
        "version": "5.15",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.15",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.6",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]