CVE-2021-47130: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47130 affects the Linux kernel's NVMe target subsystem. The vulnerability was discovered when a p2p device was found but the p2p pool was empty, causing the NVMe target to incorrectly attempt freeing an SGL from the p2p pool instead of the regular SGL pool, resulting in a system crash (Kernel Git).

The vulnerability occurs in the nvmet subsystem when handling p2pmem (peer-to-peer memory) allocations. When a p2p device is found but its pool is empty, the system attempts to free memory from the wrong pool, triggering a kernel BUG() at lib/genalloc.c:518. The issue was fixed by modifying the code to only assign the p2p_dev for the request if it was allocated from the p2p pool (Kernel Git). The vulnerability has been assigned a CVSS v3.1 Base Score of 4.4 (Medium) with vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H (NVD).

The vulnerability results in a kernel crash when specific conditions are met in the NVMe target subsystem, leading to a denial of service condition. The crash occurs during the memory deallocation process when handling peer-to-peer memory operations (Kernel Git).

The vulnerability requires local access with high privileges to trigger. It specifically occurs when using NVMe target functionality with peer-to-peer memory operations, making it relatively difficult to exploit in most environments (NVD).

The issue has been fixed in the Linux kernel through a patch that modifies the p2p_dev assignment logic. The fix ensures that p2p_dev is only assigned when memory is actually allocated from the p2p pool (Kernel Git).