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LinuxCVE-2024-40910

HistoryJul 12, 2024 - 1:15 p.m.

CVE-2024-40910

2024-07-1213:15:14

Linux

web.nvd.nist.gov

linux

kernel

ax25

vulnerability

fix

imbalance

refcount

inbound connections

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

6.4

Confidence

Low

EPSS

Percentile

5.1%

JSON

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

ax25: Fix refcount imbalance on inbound connections

When releasing a socket in ax25_release(), we call netdev_put() to
decrease the refcount on the associated ax.25 device. However, the
execution path for accepting an incoming connection never calls
netdev_hold(). This imbalance leads to refcount errors, and ultimately
to kernel crashes.

A typical call trace for the above situation will start with one of the
following errors:

refcount_t: decrement hit 0; leaking memory.
refcount_t: underflow; use-after-free.

And will then have a trace like:

Call Trace:
&lt;TASK&gt;
? show_regs+0x64/0x70
? __warn+0x83/0x120
? refcount_warn_saturate+0xb2/0x100
? report_bug+0x158/0x190
? prb_read_valid+0x20/0x30
? handle_bug+0x3e/0x70
? exc_invalid_op+0x1c/0x70
? asm_exc_invalid_op+0x1f/0x30
? refcount_warn_saturate+0xb2/0x100
? refcount_warn_saturate+0xb2/0x100
ax25_release+0x2ad/0x360
__sock_release+0x35/0xa0
sock_close+0x19/0x20
[...]

On reboot (or any attempt to remove the interface), the kernel gets
stuck in an infinite loop:

unregister_netdevice: waiting for ax0 to become free. Usage count = 0

This patch corrects these issues by ensuring that we call netdev_hold()
and ax25_dev_hold() for new connections in ax25_accept(). This makes the
logic leading to ax25_accept() match the logic for ax25_bind(): in both
cases we increment the refcount, which is ultimately decremented in
ax25_release().

Affected configurations

Nvd

Vulners

Node

linuxlinux_kernelRange5.18–6.1.95

linuxlinux_kernelRange6.2–6.6.35

linuxlinux_kernelRange6.7–6.9.6

linuxlinux_kernelMatch6.10rc1

linuxlinux_kernelMatch6.10rc2

VendorProductVersionCPE
linuxlinux_kernel*cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
linuxlinux_kernel6.10cpe:2.3:o:linux:linux_kernel:6.10:rc1:*:*:*:*:*:*
linuxlinux_kernel6.10cpe:2.3:o:linux:linux_kernel:6.10:rc2:*:*:*:*:*:*

Vendor	Product	Version	CPE
linux	linux_kernel	*	cpe:2.3:o:linux:linux_kernel::::::::
linux	linux_kernel	6.10	cpe:2.3:o:linux:linux_kernel:6.10:rc1::::::
linux	linux_kernel	6.10	cpe:2.3:o:linux:linux_kernel:6.10:rc2::::::

CNA Affected

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/ax25/af_ax25.c"
    ],
    "versions": [
      {
        "version": "9fd75b66b8f6",
        "lessThan": "f4df9d6c8d4e",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9fd75b66b8f6",
        "lessThan": "52100fd74ad0",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9fd75b66b8f6",
        "lessThan": "a723a6c8d483",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "9fd75b66b8f6",
        "lessThan": "3c34fb0bd4a4",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "net/ax25/af_ax25.c"
    ],
    "versions": [
      {
        "version": "5.18",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.18",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.1.95",
        "lessThanOrEqual": "6.1.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.6.35",
        "lessThanOrEqual": "6.6.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.9.6",
        "lessThanOrEqual": "6.9.*",
        "status": "unaffected",
        "versionType": "custom"
      },
      {
        "version": "6.10",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]