CVE-2021-3483: 
Linux Kernel vulnerability analysis and mitigation

A flaw was discovered in the Nosy driver in the Linux kernel (CVE-2021-3483), affecting versions prior to 5.12-rc6. The vulnerability was discovered by 马哲宇 (Zheyu Ma) and disclosed on April 7, 2021. The issue affects the IEEE 1394 (Firewire) nosy packet sniffer driver, which is used for protocol analysis and development of IEEE 1394 drivers, applications, or firmware (Openwall List).

The vulnerability occurs in the Linux/drivers/firewire/nosy.c file. For each device, the nosy driver allocates a pcilynx structure. The issue allows a device to be inserted twice into a doubly-linked list, which leads to a use-after-free condition when one of these devices is removed. The vulnerability has been assigned a CVSS v3.1 base score of 7.8 (HIGH) with the vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD, NetApp Advisory).

The vulnerability poses significant threats to system security, potentially affecting confidentiality, integrity, and system availability. When successfully exploited, it could lead to disclosure of sensitive information, addition or modification of data, or Denial of Service (DoS). On systems using the affected driver, local users with access to /dev/nosy could potentially cause system crashes, memory corruption, or achieve privilege escalation (Debian Advisory, NetApp Advisory).

The vulnerability was fixed in Linux kernel version 5.12-rc6 through a patch that addresses the doubly-linked list issue. The fix was committed with ID 829933ef05a951c8ff140e814656d73e74915faf. Various Linux distributions have backported the fix to their supported kernel versions, including Ubuntu, Debian, and Red Hat (Debian Advisory, Red Hat Bugzilla).