发布于3月6日3月6日 Members Debian: CVE-2021-47281: linux -- security update Severity 7 CVSS (AV:L/AC:M/Au:S/C:C/I:C/A:C) Published 05/21/2024 Created 07/31/2024 Added 07/30/2024 Modified 01/30/2025 Description In the Linux kernel, the following vulnerability has been resolved: ALSA: seq: Fix race of snd_seq_timer_open() The timer instance per queue is exclusive, and snd_seq_timer_open() should have managed the concurrent accesses.It looks as if it's checking the already existing timer instance at the beginning, but it's not right, because there is no protection, hence any later concurrent call of snd_seq_timer_open() may override the timer instance easily.This may result in UAF, as the leftover timer instance can keep running while the queue itself gets closed, as spotted by syzkaller recently. For avoiding the race, add a proper check at the assignment of tmr->timeri again, and return -EBUSY if it's been already registered. Solution(s) debian-upgrade-linux References https://attackerkb.com/topics/cve-2021-47281 CVE - 2021-47281
