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{"bugzilla": {"description": "kernel: ALSA: seq: Fix race of snd_seq_timer_open()", "id": "2282516", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2282516"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.8", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:H", "status": "draft"}, "cwe": "CWE-416", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nALSA: seq: Fix race of snd_seq_timer_open()\nThe timer instance per queue is exclusive, and snd_seq_timer_open()\nshould have managed the concurrent accesses. It looks as if it's\nchecking the already existing timer instance at the beginning, but\nit's not right, because there is no protection, hence any later\nconcurrent call of snd_seq_timer_open() may override the timer\ninstance easily. This may result in UAF, as the leftover timer\ninstance can keep running while the queue itself gets closed, as\nspotted by syzkaller recently.\nFor avoiding the race, add a proper check at the assignment of\ntmr->timeri again, and return -EBUSY if it's been already registered.", "A vulnerability was found in the Linux kernel's ALSA sequencer, where the snd_seq_timer_open() function fails to properly manage concurrent access to timer instances, which could allow multiple calls to override the timer, leading to a potential use-after-free issue if a timer continues running after its associated queue is closed."], "mitigation": {"lang": "en:us", "value": "Red Hat has investigated whether a possible mitigation exists for this issue, and has not been able to identify a practical example. Please update the affected package as soon as possible."}, "name": "CVE-2021-47281", "package_state": [{"cpe": "cpe:/o:redhat:enterprise_linux:6", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 6"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:7", "fix_state": "Out of support scope", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 7"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:8", "fix_state": "Affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 8"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel", "product_name": "Red Hat Enterprise Linux 9"}, {"cpe": "cpe:/o:redhat:enterprise_linux:9", "fix_state": "Not affected", "package_name": "kernel-rt", "product_name": "Red Hat Enterprise Linux 9"}], "public_date": "2024-05-21T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2021-47281\nhttps://nvd.nist.gov/vuln/detail/CVE-2021-47281\nhttps://lore.kernel.org/linux-cve-announce/2024052153-CVE-2021-47281-d193@gregkh/T"], "threat_severity": "Moderate"}