CVE-2023-53728
0.04%V4
2025-10-22
14h15 +00:00
14h15 +00:00
特定のCVEの通知
特定のCVEの変更情報をいち早くお届けします。
CVE の説明
In the Linux kernel, the following vulnerability has been resolved:
posix-timers: Ensure timer ID search-loop limit is valid
posix_timer_add() tries to allocate a posix timer ID by starting from the
cached ID which was stored by the last successful allocation.
This is done in a loop searching the ID space for a free slot one by
one. The loop has to terminate when the search wrapped around to the
starting point.
But that's racy vs. establishing the starting point. That is read out
lockless, which leads to the following problem:
CPU0 CPU1
posix_timer_add()
start = sig->posix_timer_id;
lock(hash_lock);
... posix_timer_add()
if (++sig->posix_timer_id < 0)
start = sig->posix_timer_id;
sig->posix_timer_id = 0;
So CPU1 can observe a negative start value, i.e. -1, and the loop break
never happens because the condition can never be true:
if (sig->posix_timer_id == start)
break;
While this is unlikely to ever turn into an endless loop as the ID space is
huge (INT_MAX), the racy read of the start value caught the attention of
KCSAN and Dmitry unearthed that incorrectness.
Rewrite it so that all id operations are under the hash lock.
CVE の情報
EPSS
EPSSは脆弱性が悪用される可能性を予測するスコアリングモデルです。
EPSSスコア
EPSSモデルは0から1（0〜100%）の確率スコアを算出します。スコアが高いほど、脆弱性が悪用される可能性が高いことを示します。
EPSSパーセンタイル
パーセンタイルはCVEをEPSSスコアで順位付けするために使用されます。例えば、EPSSスコアで95パーセンタイルにあるCVEは、他の95%のCVEよりも悪用される可能性が高いことを意味します。パーセンタイルはCVEのEPSSスコアを他のCVEと比較するために使用されます。
