In the Linux kernel, the following vulnerability has been resolved:
fs/eventpoll: fix endless busy loop after timeout has expired
After commit 0a65bc27bd64 ("eventpoll: Set epoll timeout if it's in
the future"), the following program would immediately enter a busy
loop in the kernel:
```
int main() {
int e = epoll_create1(0);
struct epoll_event event = {.events = EPOLLIN};
epoll_ctl(e, EPOLL_CTL_ADD, 0, &event);
const struct timespec timeout = {.tv_nsec = 1};
epoll_pwait2(e, &event, 1, &timeout, 0);
}
```
This happens because the given (non-zero) timeout of 1 nanosecond
usually expires before ep_poll() is entered and then
ep_schedule_timeout() returns false, but `timed_out` is never set
because the code line that sets it is skipped. This quickly turns
into a soft lockup, RCU stalls and deadlocks, inflicting severe
headaches to the whole system.
When the timeout has expired, we don't need to schedule a hrtimer, but
we should set the `timed_out` variable. Therefore, I suggest moving
the ep_schedule_timeout() check into the `timed_out` expression
instead of skipping it.
brauner: Note that there was an earlier fix by Joe Damato in response to
my bug report in [1].
CVSS
No CVSS.
References
Configurations
No configuration.
History
18 Jun 2025, 10:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-06-18 10:15
Updated : 2025-06-18 13:46
NVD link : CVE-2025-38017
Mitre link : CVE-2025-38017
CVE.ORG link : CVE-2025-38017
JSON object : View
Products Affected
No product.
CWE
No CWE.