Описание
In the Linux kernel, the following vulnerability has been resolved:
ALSA: pcm: set timer->private_data before registering the PCM timer
snd_pcm_timer_init() calls snd_device_register() to link the new
struct snd_timer into the global timer list while it still carries
hw.c_resolution = snd_pcm_timer_resolution (and hw.start/hw.stop),
and only afterwards sets timer->private_data = substream.
Once the timer is on the list under register_mutex, a concurrent
reader can already reach it through the same mutex and invoke these
callbacks. /proc/asound/timers does this via c_resolution(), and
snd_timer_open()+snd_timer_start() reach start()/stop() the same way.
All three dereference timer->private_data, which for this brief
window is NULL, giving a NULL-pointer dereference:
substream = timer->private_data;
return substream->runtime ? ... // substream is NULL
Move the private_data/private_free assignment before
snd_device_register() so the timer is never visible on the list
without its private_data set. On the snd_device_register() failure
path, private_free() (snd_pcm_timer_free()) can now run, but it only
does substream->timer = NULL, which is already NULL at that point
since substream->timer is set to the new timer just once, after a
successful registration -- so the failure path stays safe.
A flaw was found in the Linux kernel's ALSA (Advanced Linux Sound Architecture) subsystem. A race condition during audio timer registration allows a new timer to become accessible to other processes before its internal data is initialized. A local user can exploit this vulnerability by concurrently accessing the timer interface, triggering a NULL-pointer dereference. This flaw results in a kernel crash, leading to a Denial of Service (DoS).
Отчет
This vulnerability is rated as Moderate impact because successful exploitation requires local authenticated access and winning a precise race condition, with the blast radius confined to an operating system crash. In typical Red Hat Enterprise Linux server environments, audio hardware and services are rarely utilized, significantly limiting exposure. On systems where sound components are active, an unprivileged local user could induce a denial of service by triggering the uninitialized timer dereference, though arbitrary code execution and information disclosure are not possible.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Affected | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 8 | kernel | Affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Affected | ||
| Red Hat Enterprise Linux 9 | kernel | Affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Affected | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Affected | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Affected |
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Дополнительная информация
Статус:
EPSS
7 High
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: set timer->private_data before registering the PCM timer snd_pcm_timer_init() calls snd_device_register() to link the new struct snd_timer into the global timer list while it still carries hw.c_resolution = snd_pcm_timer_resolution (and hw.start/hw.stop), and only afterwards sets timer->private_data = substream. Once the timer is on the list under register_mutex, a concurrent reader can already reach it through the same mutex and invoke these callbacks. /proc/asound/timers does this via c_resolution(), and snd_timer_open()+snd_timer_start() reach start()/stop() the same way. All three dereference timer->private_data, which for this brief window is NULL, giving a NULL-pointer dereference: substream = timer->private_data; return substream->runtime ? ... // substream is NULL Move the private_data/private_free assignment before snd_device_register() so the timer is never visible on the list without its priv...
In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: set timer->private_data before registering the PCM timer snd_pcm_timer_init() calls snd_device_register() to link the new struct snd_timer into the global timer list while it still carries hw.c_resolution = snd_pcm_timer_resolution (and hw.start/hw.stop), and only afterwards sets timer->private_data = substream. Once the timer is on the list under register_mutex, a concurrent reader can already reach it through the same mutex and invoke these callbacks. /proc/asound/timers does this via c_resolution(), and snd_timer_open()+snd_timer_start() reach start()/stop() the same way. All three dereference timer->private_data, which for this brief window is NULL, giving a NULL-pointer dereference: substream = timer->private_data; return substream->runtime ? ... // substream is NULL Move the private_data/private_free assignment before snd_device_register() so the timer is never visible on the list without it
ALSA: pcm: set timer->private_data before registering the PCM timer
In the Linux kernel, the following vulnerability has been resolved: A ...
In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: set timer->private_data before registering the PCM timer snd_pcm_timer_init() calls snd_device_register() to link the new struct snd_timer into the global timer list while it still carries hw.c_resolution = snd_pcm_timer_resolution (and hw.start/hw.stop), and only afterwards sets timer->private_data = substream. Once the timer is on the list under register_mutex, a concurrent reader can already reach it through the same mutex and invoke these callbacks. /proc/asound/timers does this via c_resolution(), and snd_timer_open()+snd_timer_start() reach start()/stop() the same way. All three dereference timer->private_data, which for this brief window is NULL, giving a NULL-pointer dereference: substream = timer->private_data; return substream->runtime ? ... // substream is NULL Move the private_data/private_free assignment before snd_device_register() so the timer is never visible on the list without...
EPSS
7 High
CVSS3