Linux Kernel __mdiobus_register() Function Denial of Service Vulnerability [CVE-2019-12819]

CVE Number – CVE-2019-12819

A vulnerability in the Linux Kernel could allow a local attacker to cause a denial of service (DoS) condition on a targeted system.The vulnerability exists in the __mdiobus_register() function, as defined in the drivers/net/phy/mdio_bus.c source code file of the affected software. An attacker could exploit the vulnerability by accessing the system and executing an application that submits malicious input to the affected software. A successful exploit could cause a use-after-free condition in the fixed_mdio_bus_init function, resulting in a DoS condition.Proof-of-concept (PoC) code that demonstrates an exploit of this vulnerability is publicly available.Kernel.org has confirmed the vulnerability and released software updates.

Analysis

• To exploit this vulnerability, the attacker must have user-level access to the targeted system. This access requirement could reduce the likelihood of a successful exploit.

Safeguards

• Administrators are advised to apply the appropriate updates.
  
  Administrators are advised to allow only trusted users to have network access.
  
  Administrators are advised to run both firewall and antivirus applications to minimize the potential of inbound and outbound threats.
  
  Administrators may consider using IP-based access control lists (ACLs) to allow only trusted systems to access the affected systems.
  
  Administrators can help protect affected systems from external attacks by using a solid firewall strategy.
  
  Administrators are advised to monitor affected systems.

Vendor Announcements

• Kernel.org has published a git commit and changelog at the following links: mdio_bus: Fix use-after-free on device_register fails and Linux Kernel 4.20.17

Fixed Software

• Kernel.org has released software updates at the following link: Linux Kernel Archives