CVE-2021-47442: 
Linux Kernel vulnerability analysis and mitigation

CVE-2021-47442 is a memory leak vulnerability discovered in the Linux kernel's NFC digital subsystem. The vulnerability specifically affects the digital_in_send_sdd_req() function where a memory leak occurs when digital_in_send_cmd() fails, as the allocated 'skb' is not properly freed (CVE Details).

The vulnerability exists in the NFC digital subsystem of the Linux kernel. When the digital_in_send_sdd_req() function allocates an 'skb' (socket buffer) and calls digital_in_send_cmd(), a memory leak occurs if digital_in_send_cmd() fails because the allocated memory is not freed in the error path. The fix involves adding proper cleanup by freeing the 'skb' if digital_in_send_cmd() returns an error (Kernel Commit).

The vulnerability results in a memory leak in the Linux kernel's NFC subsystem. When triggered, it can lead to gradual system memory depletion, potentially affecting system performance and stability over time (Debian Security).

The vulnerability has been fixed in multiple Linux kernel versions. The fix involves properly freeing the 'skb' when digital_in_send_cmd() fails. The patch has been backported to various stable kernel versions including 5.10.x, 5.15.x, and 6.1.x series. Users should update their Linux kernel to a patched version (Debian Security).