CVE-2021-47298: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47298 is a memory leak vulnerability discovered in the Linux kernel's BPF sockmap functionality. The vulnerability was identified during a code review and affects Linux kernel versions from 5.10 through 5.13.6, as well as 5.14-rc1 and 5.14-rc2. The issue occurs in the error handling path when skb_linearize fails, potentially leading to a memory leak (NVD).

The vulnerability exists in the Linux kernel's network core subsystem, specifically in the skmsg.c file. The issue occurs when skb_linearize is needed and fails, which could lead to a memory leak in the msg block during error handling. The vulnerability has been assigned a CVSS v3.1 Base Score of 5.5 (Medium) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H. The vulnerability is classified as CWE-401: Missing Release of Memory after Effective Lifetime (NVD).

The primary impact of this vulnerability is a potential memory leak in the Linux kernel, which could lead to resource exhaustion and system performance degradation. The vulnerability affects the system's availability but does not compromise confidentiality or integrity (NVD).

The vulnerability requires local access and low privileges to exploit. It occurs in an unlikely error case scenario when skb_linearize fails during packet processing in the BPF sockmap functionality (Kernel Patch).

The vulnerability has been fixed by ensuring proper memory cleanup in the error handling path. The fix involves adding proper kfree(msg) calls before returning errors in the affected functions. The patch has been merged into the Linux kernel, and users should upgrade to patched versions (Kernel Patch).