{"dataType": "CVE_RECORD", "dataVersion": "5.1", "cveMetadata": {"cveId": "CVE-2021-47281", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-21T13:27:52.128Z", "datePublished": "2024-05-21T14:20:07.499Z", "dateUpdated": "2024-11-04T12:02:54.252Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2024-11-04T12:02:54.252Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: Fix race of snd_seq_timer_open()\n\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.\n\nFor avoiding the race, add a proper check at the assignment of\ntmr->timeri again, and return -EBUSY if it's been already registered."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["sound/core/seq/seq_timer.c"], "versions": [{"version": "1da177e4c3f4", "lessThan": "bd7d88b0874f", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f4", "lessThan": "536a7646c00a", "status": "affected", "versionType": "git"}, {"version": "1da177e4c3f4", "lessThan": "83e197a8414c", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["sound/core/seq/seq_timer.c"], "versions": [{"version": "5.10.44", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.12.11", "lessThanOrEqual": "5.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix"}]}], "references": [{"url": "https://git.kernel.org/stable/c/bd7d88b0874f82f7b29d1a53e574cedaf23166ba"}, {"url": "https://git.kernel.org/stable/c/536a7646c00a0f14fee49e5e313109e5da2f6031"}, {"url": "https://git.kernel.org/stable/c/83e197a8414c0ba545e7e3916ce05f836f349273"}], "title": "ALSA: seq: Fix race of snd_seq_timer_open()", "x_generator": {"engine": "bippy-9e1c9544281a"}}, "adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2021-47281", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2024-05-23T21:20:28.570330Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:13:56.494Z"}}, {"providerMetadata": {"orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:32:08.027Z"}, "title": "CVE Program Container", "references": [{"url": "https://git.kernel.org/stable/c/bd7d88b0874f82f7b29d1a53e574cedaf23166ba", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/536a7646c00a0f14fee49e5e313109e5da2f6031", "tags": ["x_transferred"]}, {"url": "https://git.kernel.org/stable/c/83e197a8414c0ba545e7e3916ce05f836f349273", "tags": ["x_transferred"]}]}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: seq: Fix race of snd_seq_timer_open()\n\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.\n\nFor avoiding the race, add a proper check at the assignment of\ntmr->timeri again, and return -EBUSY if it's been already registered."}, {"lang": "es", "value": "En el kernel de Linux se ha resuelto la siguiente vulnerabilidad: ALSA: seq: Fix race of snd_seq_timer_open(). La instancia del temporizador por cola es exclusiva, y snd_seq_timer_open() deber\u00eda haber gestionado los accesos concurrentes. Parece como si estuviera verificando la instancia del temporizador ya existente al principio, pero no es correcto, porque no hay protecci\u00f3n, por lo tanto, cualquier llamada simult\u00e1nea posterior a snd_seq_timer_open() puede anular la instancia del temporizador f\u00e1cilmente. Esto puede resultar en UAF, ya que la instancia del temporizador sobrante puede seguir ejecut\u00e1ndose mientras la cola se cierra, como descubri\u00f3 syzkaller recientemente. Para evitar la ejecuci\u00f3n, agregue una verificaci\u00f3n adecuada en la asignaci\u00f3n de tmr->timeri nuevamente y devuelva -EBUSY si ya se registr\u00f3."}], "id": "CVE-2021-47281", "lastModified": "2024-05-21T16:54:26.047", "metrics": {}, "published": "2024-05-21T15:15:16.353", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/536a7646c00a0f14fee49e5e313109e5da2f6031"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/83e197a8414c0ba545e7e3916ce05f836f349273"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/bd7d88b0874f82f7b29d1a53e574cedaf23166ba"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Awaiting Analysis"}

{"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", "upstream_fix": "kernel 5.10.44, kernel 5.12.11, kernel 5.13"}