CVE-2021-47483: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47483 is a vulnerability in the Linux kernel's regmap subsystem, specifically in the regcache_rbtree_exit() function. The vulnerability was discovered in 2021 and affects Linux kernel versions from 3.12 up to versions before 4.4.291, 4.9.289, 4.14.254, and 4.19.215. The issue occurs in the error handling path of regcache_rbtree_init() where a double-free condition can be triggered (NVD).

The vulnerability occurs in regcache_rbtree_insert_to_block() when a 'present' realloc operation fails. In this scenario, the 'blk' pointer, which is supposed to be assigned to 'rbnode->block', is freed, causing 'rbnode->block' to point to freed memory. Subsequently, in the error handling path of regcache_rbtree_init(), 'rbnode->block' is freed again in regcache_rbtree_exit(), resulting in a double-free condition. The vulnerability has a CVSS v3.1 Base Score of 7.8 (HIGH) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The vulnerability can lead to a kernel crash through a double-free condition, which could potentially be exploited for denial of service (DoS) attacks. The high CVSS score indicates potential for significant impact on system confidentiality, integrity, and availability if exploited (NVD).

The vulnerability requires local access with low privileges to exploit. The attack complexity is low, and no user interaction is required for exploitation. The issue can be triggered through the regmap subsystem's error handling paths (NVD).

The vulnerability has been fixed by moving up the assignment of rbnode->block to immediately after the reallocation has succeeded, ensuring that the data structure stays valid even if the second reallocation fails. The fix is available in kernel versions 4.4.291, 4.9.289, 4.14.254, and 4.19.215 and later (Kernel Patch).