CVE-2025-37816: 
Linux Debian vulnerability analysis and mitigation

In the Linux kernel, a vulnerability has been identified and resolved in the mei: vsc: component. The issue stems from an invalid use of the countedby() attribute in vsctppacket.buf[], where gcc 15 honors the _countedby(len) attribute but the code uses it incorrectly. The len parameter contains the actual packet length without the CRC rather than the available buffer size, leading to a buffer overflow condition when vsctp_xfer() attempts to add the CRC to buf[] (NVD).

The vulnerability occurs when the vsctpxfer() function attempts to add CRC to buf[], triggering a fortify-panic handler due to incorrect buffer size calculation. The issue manifests as a 4-byte write attempt to a buffer of size 0, as evidenced by the error message: 'memcpy: detected buffer overflow: 4 byte write of buffer size 0'. This triggers a CPU warning and fortify panic in the kernel (NVD).

When exploited, this vulnerability can lead to buffer overflow conditions in the Linux kernel's mei: vsc component. The immediate impact is a system panic when the fortify handler detects the overflow attempt, which could result in system instability or denial of service (NVD).

A fix has been implemented by restructuring the vsctppacket struct definition. Instead of simply removing the counted-by attribute, the solution involves splitting the struct into a header and a full-packet definition, using a fixed size buf[] in the packet definition. This approach maintains the effectiveness of fortify-source buffer overrun checking while correctly handling the buffer size (NVD).