The Linux kernel's coresight ultrasoc-smb driver contained a vulnerability where the smb_sync_perf_buffer() function could perform an out-of-bounds write. This happens when the SMB sink is used as a perf AUX sink and the function derives a page index from the head pointer without first normalizing it against the buffer size. The lack of normalization before the first loop iteration allows the page index to exceed the bounds of the destination pages array, leading to a potential memory corruption. The fix involves normalizing the head pointer modulo the AUX buffer size before calculating the page index and offset, aligning with the approach used in tmc_etr_sync_perf_buffer().

This vulnerability can cause an out-of-bounds write in kernel memory, which may lead to memory corruption. The specific impact depends on how the corrupted memory is used, but it could potentially affect system stability or security. No known exploits in the wild have been reported.

Patch status is not yet confirmed — check the vendor advisory for current remediation guidance. Since this is a Linux kernel vulnerability, monitor official Linux kernel releases and apply updates that address CVE-2026-64402 when available.