CVE-2024-50207

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> ring-buffer: Fix reader locking when changing the sub buffer order<br /> <br /> The function ring_buffer_subbuf_order_set() updates each<br /> ring_buffer_per_cpu and installs new sub buffers that match the requested<br /> page order. This operation may be invoked concurrently with readers that<br /> rely on some of the modified data, such as the head bit (RB_PAGE_HEAD), or<br /> the ring_buffer_per_cpu.pages and reader_page pointers. However, no<br /> exclusive access is acquired by ring_buffer_subbuf_order_set(). Modifying<br /> the mentioned data while a reader also operates on them can then result in<br /> incorrect memory access and various crashes.<br /> <br /> Fix the problem by taking the reader_lock when updating a specific<br /> ring_buffer_per_cpu in ring_buffer_subbuf_order_set().