ALSA: timer: don't re-enter an instance callback that is still running
In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: don't re-enter an instance callback that is still running The userspace-driven timer (utimer) TRIGGER ioctl calls snd_timer_interrupt() directly with no serialization, so two threads triggering the same utimer can run snd_timer_interrupt() on one snd_timer concurrently. snd_timer_process_callbacks() drops timer->lock around each instance callback and marks the in-flight callback with the single SNDRV_TIMER_IFLG_CALLBACK bit; snd_timer_close_locked() waits on that bit to drain an in-flight callback before freeing the instance. The bit cannot represent two concurrent callbacks: when a second interrupt re-queues an instance whose callback is still running, both run at once, the first to finish clears the bit, and the close-path drain then frees the instance (and its callback_data) while the other callback is still live - a use-after-free reachable by any user able to open /dev/snd/timer, both via a user timer instance and via a sequencer queue timer bound to the utimer. snd_timer_interrupt() sets IFLG_CALLBACK before dropping timer->lock, so a concurrent interrupt already observes it under the lock. Skip re-queuing an instance (and its slaves) to the ack/sack list while its callback is in flight; the accumulated pticks are delivered on the next tick, so no event is lost.
CVE-2026-68200
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-68200
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "37745918e0e7575bc40f38da93a99b9fa6406224",
"lessThan": "996c24377eea4d4506b7c3ccbbf1e490440b5e0b",
"versionType": "git"
},
{
"status": "affected",
"version": "37745918e0e7575bc40f38da93a99b9fa6406224",
"lessThan": "1395327a96614885552bae5fbb650e6dd182d49b",
"versionType": "git"
},
{
"status": "affected",
"version": "37745918e0e7575bc40f38da93a99b9fa6406224",
"lessThan": "c1078130a4cd7e738f4b73afe99b3e68cbfbf884",
"versionType": "git"
},
{
"status": "affected",
"version": "37745918e0e7575bc40f38da93a99b9fa6406224",
"lessThan": "70d28bfcd6224eed75986b3b987b997e59643fa4",
"versionType": "git"
}
],
"programFiles": [
"sound/core/timer.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6.12"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "6.12",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "6.12.101",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.42",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.1.6",
"versionType": "semver",
"lessThanOrEqual": "7.1.*"
},
{
"status": "unaffected",
"version": "7.2",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"sound/core/timer.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-68200
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #41154 · Revision 1
- Added to Heist Feed
- Publisher date