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LinuxCVE-2022-48838

HistoryJul 16, 2024 - 1:15 p.m.

CVE-2022-48838

2024-07-1613:15:11

CWE-416

Linux

web.nvd.nist.gov

linux kernel

usb gadget

use-after-free

vulnerability fix

CVSS3

5.5

Attack Vector

LOCAL

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

NONE

Integrity Impact

NONE

Availability Impact

HIGH

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

AI Score

6.5

Confidence

Low

EPSS

Percentile

5.1%

JSON

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

usb: gadget: Fix use-after-free bug by not setting udc->dev.driver

The syzbot fuzzer found a use-after-free bug:

BUG: KASAN: use-after-free in dev_uevent+0x712/0x780 drivers/base/core.c:2320
Read of size 8 at addr ffff88802b934098 by task udevd/3689

CPU: 2 PID: 3689 Comm: udevd Not tainted 5.17.0-rc4-syzkaller-00229-g4f12b742eb2b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0x8d/0x303 mm/kasan/report.c:255
__kasan_report mm/kasan/report.c:442 [inline]
kasan_report.cold+0x83/0xdf mm/kasan/report.c:459
dev_uevent+0x712/0x780 drivers/base/core.c:2320
uevent_show+0x1b8/0x380 drivers/base/core.c:2391
dev_attr_show+0x4b/0x90 drivers/base/core.c:2094

Although the bug manifested in the driver core, the real cause was a
race with the gadget core. dev_uevent() does:

if (dev-&gt;driver)
	add_uevent_var(env, "DRIVER=%s", dev-&gt;driver-&gt;name);

and between the test and the dereference of dev->driver, the gadget
core sets dev->driver to NULL.

The race wouldn’t occur if the gadget core registered its devices on
a real bus, using the standard synchronization techniques of the
driver core. However, it’s not necessary to make such a large change
in order to fix this bug; all we need to do is make sure that
udc->dev.driver is always NULL.

In fact, there is no reason for udc->dev.driver ever to be set to
anything, let alone to the value it currently gets: the address of the
gadget’s driver. After all, a gadget driver only knows how to manage
a gadget, not how to manage a UDC.

This patch simply removes the statements in the gadget core that touch
udc->dev.driver.

Affected configurations

Nvd

Vulners

Node

linuxlinux_kernelRange3.1–4.9.308

linuxlinux_kernelRange4.10–4.14.273

linuxlinux_kernelRange4.15–4.19.236

linuxlinux_kernelRange4.20–5.4.187

linuxlinux_kernelRange5.5–5.10.108

linuxlinux_kernelRange5.11–5.15.31

linuxlinux_kernelRange5.16–5.16.17

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/usb/gadget/udc/core.c"
    ],
    "versions": [
      {
        "version": "2ccea03a8f7e",
        "lessThan": "4325124dde67",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "e2d3a7009e50",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "609a7119bffe",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "2282a6eb6d4e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "00bdd9bf1ac6",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "2015c23610cd",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "27d64436984f",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "2ccea03a8f7e",
        "lessThan": "16b1941eac2b",
        "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/usb/gadget/udc/core.c"
    ],
    "versions": [
      {
        "version": "3.1",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "3.1",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.9.308",
        "lessThanOrEqual": "4.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.14.273",
        "lessThanOrEqual": "4.14.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "4.19.236",
        "lessThanOrEqual": "4.19.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.4.187",
        "lessThanOrEqual": "5.4.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.10.108",
        "lessThanOrEqual": "5.10.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.15.31",
        "lessThanOrEqual": "5.15.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.16.17",
        "lessThanOrEqual": "5.16.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "5.17",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]