Описание
In the Linux kernel, the following vulnerability has been resolved:
mm/damon/core: fix damos_walk() vs kdamond_fn() exit race
When kdamond_fn() main loop is finished, the function cancels remaining
damos_walk() request and unset the damon_ctx->kdamond so that API callers
and API functions themselves can show the context is terminated.
damos_walk() adds the caller's request to the queue first. After that, it
shows if the kdamond of the damon_ctx is still running (damon_ctx->kdamond
is set). Only if the kdamond is running, damos_walk() starts waiting for
the kdamond's handling of the newly added request.
The damos_walk() requests registration and damon_ctx->kdamond unset are
protected by different mutexes, though. Hence, damos_walk() could race
with damon_ctx->kdamond unset, and result in deadlocks.
For example, let's suppose kdamond successfully finished the damow_walk()
request cancelling. Right after that, damos_walk() is called for the
context. It registers the new request, and shows the context is still
running, because damon_ctx->kdamond unset is not yet done. Hence the
damos_walk() caller starts waiting for the handling of the request.
However, the kdamond is already on the termination steps, so it never
handles the new request. As a result, the damos_walk() caller thread
infinitely waits.
Fix this by introducing another damon_ctx field, namely
walk_control_obsolete. It is protected by the
damon_ctx->walk_control_lock, which protects damos_walk() request
registration. Initialize (unset) it in kdamond_fn() before letting
damon_start() returns and set it just before the cancelling of the
remaining damos_walk() request is executed. damos_walk() reads the
obsolete field under the lock and avoids adding a new request.
After this change, only requests that are guaranteed to be handled or
cancelled are registered. Hence the after-registration DAMON context
termination check is no longer needed. Remove it together.
The issue is found by sashiko [1].
A flaw was found in the Linux kernel's Data Access MONitor (DAMON) subsystem. A race condition exists in the memory management component, specifically during the exit process of kdamond_fn() and the registration of damos_walk() requests. This vulnerability allows a local attacker to trigger a deadlock, resulting in a Denial of Service (DoS) for the affected system.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat Enterprise Linux 10 | kernel | Not affected | ||
| Red Hat Enterprise Linux 6 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel | Not affected | ||
| Red Hat Enterprise Linux 7 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel | Not affected | ||
| Red Hat Enterprise Linux 8 | kernel-rt | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel | Not affected | ||
| Red Hat Enterprise Linux 9 | kernel-rt | Not affected |
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Дополнительная информация
EPSS
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: mm/damon/core: fix damos_walk() vs kdamond_fn() exit race When kdamond_fn() main loop is finished, the function cancels remaining damos_walk() request and unset the damon_ctx->kdamond so that API callers and API functions themselves can show the context is terminated. damos_walk() adds the caller's request to the queue first. After that, it shows if the kdamond of the damon_ctx is still running (damon_ctx->kdamond is set). Only if the kdamond is running, damos_walk() starts waiting for the kdamond's handling of the newly added request. The damos_walk() requests registration and damon_ctx->kdamond unset are protected by different mutexes, though. Hence, damos_walk() could race with damon_ctx->kdamond unset, and result in deadlocks. For example, let's suppose kdamond successfully finished the damow_walk() request cancelling. Right after that, damos_walk() is called for the context. It registers the new request, a...
In the Linux kernel, the following vulnerability has been resolved: mm/damon/core: fix damos_walk() vs kdamond_fn() exit race When kdamond_fn() main loop is finished, the function cancels remaining damos_walk() request and unset the damon_ctx->kdamond so that API callers and API functions themselves can show the context is terminated. damos_walk() adds the caller's request to the queue first. After that, it shows if the kdamond of the damon_ctx is still running (damon_ctx->kdamond is set). Only if the kdamond is running, damos_walk() starts waiting for the kdamond's handling of the newly added request. The damos_walk() requests registration and damon_ctx->kdamond unset are protected by different mutexes, though. Hence, damos_walk() could race with damon_ctx->kdamond unset, and result in deadlocks. For example, let's suppose kdamond successfully finished the damow_walk() request cancelling. Right after that, damos_walk() is called for the context. It registers the new request,
In the Linux kernel, the following vulnerability has been resolved: m ...
In the Linux kernel, the following vulnerability has been resolved: mm/damon/core: fix damos_walk() vs kdamond_fn() exit race When kdamond_fn() main loop is finished, the function cancels remaining damos_walk() request and unset the damon_ctx->kdamond so that API callers and API functions themselves can show the context is terminated. damos_walk() adds the caller's request to the queue first. After that, it shows if the kdamond of the damon_ctx is still running (damon_ctx->kdamond is set). Only if the kdamond is running, damos_walk() starts waiting for the kdamond's handling of the newly added request. The damos_walk() requests registration and damon_ctx->kdamond unset are protected by different mutexes, though. Hence, damos_walk() could race with damon_ctx->kdamond unset, and result in deadlocks. For example, let's suppose kdamond successfully finished the damow_walk() request cancelling. Right after that, damos_walk() is called for the context. It registers the new reque...
EPSS