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.
CVSS Details
- CVSS 3.1 Base Score: 7.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Debian | — | Upgrade linux | Jul 30, 2024 | May 21, 2024 |
| Redhat_linux | — | No solution exists | Jul 9, 2025 | May 21, 2024 |
| Suse | — | Upgrade kernel-64kb-develUpgrade kernel-preemptUpgrade kernel-macrosUpgrade kernel-symsUpgrade kernel-default-extraUpgrade kernel-zfcpdumpUpgrade kernel-devel-azureUpgrade reiserfs-kmp-defaultUpgrade kernel-default-baseUpgrade kernel-64kbUpgrade kernel-docsUpgrade kernel-develUpgrade kernel-obs-buildUpgrade kernel-default-manUpgrade kernel-azure-baseUpgrade kernel-source-azureUpgrade kernel-defaultUpgrade kernel-azure-develUpgrade kernel-preempt-develUpgrade kernel-syms-azureUpgrade kernel-default-develUpgrade kernel-azureUpgrade kernel-source | Aug 9, 2024 | May 21, 2024 |
| Ubuntu | — | No solution existsUpgrade linux-azure-fde-5.15 | Jun 26, 2025 | May 21, 2024 |
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