CVE-2021-47444: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47444 affects the Linux kernel's DRM (Direct Rendering Manager) subsystem. The vulnerability was discovered in the connector_bad_edid() function, which incorrectly handled EDID (Extended Display Identification Data) memory allocation. The issue was introduced in commit e11f5bd8228f where the function assumed the memory for EDID was large enough to hold edid[0x7e] + 1 blocks of data, ignoring the actual allocated memory size indicated by num_blocks (Kernel Commit).

The vulnerability exists in the connector_bad_edid() function within the DRM subsystem. The function failed to perform proper bounds checking when handling EDID data blocks. Specifically, it used the value from edid[0x7e] to calculate memory offsets without verifying if sufficient memory was allocated, potentially leading to out-of-bounds memory access. The issue is particularly critical when handling errors in the first block of EDID, where memory reallocation based on edid[0x7e] hasn't occurred (Red Hat CVE).

The vulnerability has been assessed with a CVSS v3 base score of 5.2 (Moderate), indicating a moderate severity level. The vulnerability could potentially lead to system instability or crashes when processing EDID data, particularly in scenarios involving display connection events (Red Hat CVE).

The vulnerability requires an attacker to have adjacent network access and high privileges to exploit. The attack complexity is considered low, but user interaction is not required for exploitation. The scope remains unchanged, with no impact on confidentiality, low impact on integrity, and high impact on availability (Red Hat CVE).

The vulnerability has been fixed by adding proper bounds checking in the connector_bad_edid() function. The fix ensures that the last_block value is compared against num_blocks before performing memory operations. Users should update their Linux kernel to a version containing the fix (Kernel Commit).