CVE-2021-47190: 
Linux Kernel vulnerability analysis and mitigation

In the Linux kernel, a memory leak vulnerability (CVE-2021-47190) was discovered in the perf_env__insert_btf() function. The issue occurs when perf_env__insert_btf() doesn't insert if a duplicate BTF id is encountered, causing a memory leak. This vulnerability affects Linux kernel versions from 5.1 up to (excluding) 5.4.162, from 5.5 up to (excluding) 5.10.82, and from 5.11 up to (excluding) 5.15.5 (NVD).

The vulnerability exists in the perf BPF subsystem where perf_env__insert_btf() function fails to properly handle memory when encountering duplicate BTF IDs. When a duplicate BTF ID is encountered, the function doesn't insert the new entry but also fails to free the allocated memory, resulting in a memory leak. The issue has been assigned a CVSS v3.1 Base Score of 5.5 (Medium) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (NVD).

The vulnerability can lead to memory leaks in the Linux kernel, potentially causing system resource exhaustion over time. This could affect system stability and potentially lead to denial of service conditions (NVD).

The vulnerability requires local access with low privileges to exploit. The attack complexity is low, and no user interaction is required. However, the impact is limited to availability through resource exhaustion (NVD).

The vulnerability has been fixed by modifying the perf_env__insert_btf() function to return a success/error value and properly free the memory if insertion doesn't happen. The fix includes adding a return -1 when the insertion error occurs in perf_env__fetch_btf. Users should upgrade to Linux kernel versions 5.4.162, 5.10.82, 5.15.5 or later to address this vulnerability (Kernel Patch).