pid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper
Historical advisory recorded 3 Nov 2026 21:57:16 UTC. Read the latest advisory.
cve-program · CVE-2026-99244
PublishedIn the Linux kernel, the following vulnerability has been resolved: pid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper Since commit 7fea700e04bd ("zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING") zap_pid_ns_processes() clears TIF_NOTIFY_SIGNAL before every kernel_wait4() call. Otherwise kernel_wait4() doesn't sleep and returns -ERESTARTSYS if signal_pending() is true and the reaper busy-waits. But clearing TIF_NOTIFY_SIGNAL doesn't fix it. It can get raised again. For example, klp_send_signals() sets it raw against any task that hasn't transitioned yet. And it keeps sending it until the livepatch finishes. The sleep loop waiting for pid_allocated to drop has the same problem and it doesn't even clear anything. So a schedule() in TASK_INTERRUPTIBLE returns immediately. Use a no_notify_signal guard. signal_pending() will ignore TIF_NOTIFY_SIGNAL and the pid namespace reaper sleeps until a child exits or free_pid() wakes it.
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cve-program · CVE-2026-99244
Publishedpid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper
In the Linux kernel, the following vulnerability has been resolved: pid_namespace: prevent TIF_NOTIFY_SIGNAL from interrupting the reaper Since commit 7fea700e04bd ("zap_pid_ns_processes: clear TIF_NOTIFY_SIGNAL along with TIF_SIGPENDING") zap_pid_ns_processes() clears TIF_NOTIFY_SIGNAL before every kernel_wait4() call. Otherwise kernel_wait4() doesn't sleep and returns -ERESTARTSYS if signal_pending() is true and the reaper busy-waits. But clearing TIF_NOTIFY_SIGNAL doesn't fix it. It can get raised again. For example, klp_send_signals() sets it raw against any task that hasn't transitioned yet. And it keeps sending it until the livepatch finishes. The sleep loop waiting for pid_allocated to drop has the same problem and it doesn't even clear anything. So a schedule() in TASK_INTERRUPTIBLE returns immediately. Use a no_notify_signal guard. signal_pending() will ignore TIF_NOTIFY_SIGNAL and the pid namespace reaper sleeps until a child exits or free_pid() wakes it.
- Source published
- 3 Nov 2026 11:15:14 UTC
- Source modified
- 3 Nov 2026 19:13:09 UTC
- Saved here
- 3 Nov 2026 21:57:16 UTC
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