In the Linux kernel, the following vulnerability has been resolved:
ALSA: timer: Forcibly close timer instances at closing
When snd_timer object is freed via snd_timer_free() and still pending
snd_timer_instance objects are assigned to the timer object, it tries
to unlink all instances and just set NULL to each ti->timer, then
releases the resources immediately. The problem is, however, when
there are slave timer instances that are associated with a master
instance linked to this timer: namely, those slave instances still
point to the freed timer object although the master instance is
unlinked, which may lead to user-after-free. The bug can be easily
triggered particularly when a new userspace-driven timers
(CONFIG_SND_UTIMER) is involved, since it can create and delete the
timer object via a simple file open/close, while the other
applications may keep accessing to that timer.
This patch is an attempt to paper over the problem above: now instead
of just unlinking, call snd_timer_close[_locked]() forcibly for each
pending timer instance, so that all assigned slave timer instances are
properly detached, too. Since snd_timer_close() might be called later
by the driver that created that instance, the check of
SNDRV_TIMER_IFLG_DEAD is added at the beginning, too.
ALSA: timer: Forcibly close timer instances at closing
When snd_timer object is freed via snd_timer_free() and still pending
snd_timer_instance objects are assigned to the timer object, it tries
to unlink all instances and just set NULL to each ti->timer, then
releases the resources immediately. The problem is, however, when
there are slave timer instances that are associated with a master
instance linked to this timer: namely, those slave instances still
point to the freed timer object although the master instance is
unlinked, which may lead to user-after-free. The bug can be easily
triggered particularly when a new userspace-driven timers
(CONFIG_SND_UTIMER) is involved, since it can create and delete the
timer object via a simple file open/close, while the other
applications may keep accessing to that timer.
This patch is an attempt to paper over the problem above: now instead
of just unlinking, call snd_timer_close[_locked]() forcibly for each
pending timer instance, so that all assigned slave timer instances are
properly detached, too. Since snd_timer_close() might be called later
by the driver that created that instance, the check of
SNDRV_TIMER_IFLG_DEAD is added at the beginning, too.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
No data.
No data.
No data.
Advisories
No advisories yet.
Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Thu, 25 Jun 2026 09:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: ALSA: timer: Forcibly close timer instances at closing When snd_timer object is freed via snd_timer_free() and still pending snd_timer_instance objects are assigned to the timer object, it tries to unlink all instances and just set NULL to each ti->timer, then releases the resources immediately. The problem is, however, when there are slave timer instances that are associated with a master instance linked to this timer: namely, those slave instances still point to the freed timer object although the master instance is unlinked, which may lead to user-after-free. The bug can be easily triggered particularly when a new userspace-driven timers (CONFIG_SND_UTIMER) is involved, since it can create and delete the timer object via a simple file open/close, while the other applications may keep accessing to that timer. This patch is an attempt to paper over the problem above: now instead of just unlinking, call snd_timer_close[_locked]() forcibly for each pending timer instance, so that all assigned slave timer instances are properly detached, too. Since snd_timer_close() might be called later by the driver that created that instance, the check of SNDRV_TIMER_IFLG_DEAD is added at the beginning, too. | |
| Title | ALSA: timer: Forcibly close timer instances at closing | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
Sign in to view the affected projects.
MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-06-25T08:39:04.346Z
Reserved: 2026-06-09T07:44:35.390Z
Link: CVE-2026-53193
Vulnrichment
No data.
NVD
No data.
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.