CVE-2026-23253

In the Linux kernel, the following vulnerability has been resolved:

media: dvb-core: fix wrong reinitialization of ringbuffer on reopen

dvb_dvr_open() calls dvb_ringbuffer_init() when a new reader opens the

DVR device. dvb_ringbuffer_init() calls init_waitqueue_head(), which

reinitializes the waitqueue list head to empty.

Since dmxdev->dvr_buffer.queue is a shared waitqueue (all opens of the

same DVR device share it), this orphans any existing waitqueue entries

from io_uring poll or epoll, leaving them with stale prev/next pointers

while the list head is reset to {self, self}.

The waitqueue and spinlock in dvr_buffer are already properly

initialized once in dvb_dmxdev_init(). The open path only needs to

reset the buffer data pointer, size, and read/write positions.

Replace the dvb_ringbuffer_init() call in dvb_dvr_open() with direct

assignment of data/size and a call to dvb_ringbuffer_reset(), which

properly resets pread, pwrite, and error with correct memory ordering

without touching the waitqueue or spinlock.