CyberRota Analysis
AI-GeneratedThe vulnerability affects the Linux kernel's ALSA subsystem, specifically the hwdep mmap callback, which improperly retains the VM_MAYWRITE flag on read-buffer mappings that should not be writable. This flaw allows a process with O_RDWR access to the hwdep node to exploit mprotect() to elevate permissions, potentially leading to unauthorized memory access and manipulation. Organizations using Linux systems, particularly those relying on ALSA for audio processing, should prioritize patching this vulnerability to mitigate risks associated with privilege escalation and memory corruption.
Original NVD Description
In the Linux kernel, the following vulnerability has been resolved: ALSA: us122l: Prevent write upgrades for read mappings The hwdep mmap callback rejects read-buffer mappings that are initially writable, but leaves VM_MAYWRITE set on mappings created with PROT_READ. A process that can open the hwdep node O_RDWR can later use mprotect() to make the mapping writable. The read allocation begins with struct usb_stream. Its read_size member is used by the fault handler to decide which pages belong to the read buffer. The read VMA intentionally remains expandable because pcm_usb_stream uses mremap() after reading that size. Changing read_size first can therefore map and access pages beyond the allocation. The same member is also consumed by usb_stream_free(), where changing it can make free_pages_exact() release pages outside the allocation. Clear VM_MAYWRITE for read-buffer mappings after rejecting an initially writable VMA. This keeps the separate output-buffer mapping writable while preventing later permission upgrades.