CVE-2026-23253media: dvb-core: fix wrong reinitialization of ringbuffer on reopen

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/527cfa8a3486b3555c5c15e2f62be484a11398dc
• https://git.kernel.org/stable/c/fb378cf89be434ed1f10ab79cc4788fba8ae868d
• https://git.kernel.org/stable/c/f1e520ca2e83ece6731af6167c9e5e16931ecba0
• https://git.kernel.org/stable/c/af050ab44fa1b1897a940d7d756e512232f5e5df
• https://git.kernel.org/stable/c/d71781bad59b1c9d60d7068004581f9bf19c0c9d
• https://git.kernel.org/stable/c/cfd94642025e6f71c8f754bdec0800ee95e4f3dd
• https://git.kernel.org/stable/c/32eb8e4adc207ef31bc6e5ae56bab940b0176066
• https://git.kernel.org/stable/c/bfbc0b5b32a8f28ce284add619bf226716a59bc0
• https://cert-portal.siemens.com/productcert/html/ssa-784472.html