{"id":"CVE-2026-68200","revision":"60cf3b7c9ccb4699b23ab7f1d20f8ebf","records":[{"revision":"60cf3b7c9ccb4699b23ab7f1d20f8ebf","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-68200","aliases":[],"title":"ALSA: timer: don't re-enter an instance callback that is still running","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: timer: don't re-enter an instance callback that is still running\n\nThe userspace-driven timer (utimer) TRIGGER ioctl calls\nsnd_timer_interrupt() directly with no serialization, so two threads\ntriggering the same utimer can run snd_timer_interrupt() on one\nsnd_timer concurrently.\n\nsnd_timer_process_callbacks() drops timer->lock around each instance\ncallback and marks the in-flight callback with the single\nSNDRV_TIMER_IFLG_CALLBACK bit; snd_timer_close_locked() waits on that\nbit to drain an in-flight callback before freeing the instance. The bit\ncannot represent two concurrent callbacks: when a second interrupt\nre-queues an instance whose callback is still running, both run at once,\nthe first to finish clears the bit, and the close-path drain then frees\nthe instance (and its callback_data) while the other callback is still\nlive - a use-after-free reachable by any user able to open\n/dev/snd/timer, both via a user timer instance and via a sequencer queue\ntimer bound to the utimer.\n\nsnd_timer_interrupt() sets IFLG_CALLBACK before dropping timer->lock, so\na concurrent interrupt already observes it under the lock. Skip\nre-queuing an instance (and its slaves) to the ack/sack list while its\ncallback is in flight; the accumulated pticks are delivered on the next\ntick, so no event is lost.","state":0,"publishedAt":"2026-08-10T12:00:19.253+00:00","modifiedAt":"2026-10-19T20:58:56.806+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"sound/core/timer.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"37745918e0e7575bc40f38da93a99b9fa6406224\",\n                            \"lessThan\": \"996c24377eea4d4506b7c3ccbbf1e490440b5e0b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"37745918e0e7575bc40f38da93a99b9fa6406224\",\n                            \"lessThan\": \"1395327a96614885552bae5fbb650e6dd182d49b\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"37745918e0e7575bc40f38da93a99b9fa6406224\",\n                            \"lessThan\": \"c1078130a4cd7e738f4b73afe99b3e68cbfbf884\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"37745918e0e7575bc40f38da93a99b9fa6406224\",\n                            \"lessThan\": \"70d28bfcd6224eed75986b3b987b997e59643fa4\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"sound/core/timer.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.12\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.12\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.101\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.42\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1.6\",\n                            \"lessThanOrEqual\": \"7.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/996c24377eea4d4506b7c3ccbbf1e490440b5e0b","https://git.kernel.org/stable/c/1395327a96614885552bae5fbb650e6dd182d49b","https://git.kernel.org/stable/c/c1078130a4cd7e738f4b73afe99b3e68cbfbf884","https://git.kernel.org/stable/c/70d28bfcd6224eed75986b3b987b997e59643fa4"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-68200","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-68200","identifiers":["CVE-2026-68200"]},"retained":false,"historicalAffected":[]}],"coverage":[]}