Vulnerability Database

309,359

Total vulnerabilities in the database

CVE-2025-38017

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].

  • Published: Jun 18, 2025
  • Updated: Nov 15, 2025
  • CVE: CVE-2025-38017
  • Severity: Medium
  • Exploit:

CVSS v3:

  • Severity: Medium
  • Score: 5.5
  • AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

No CWE or OWASP classifications available.

Software From Fixed in
linux / linux_kernel 6.14.4 6.14.8
linux / linux_kernel 6.15-rc3 6.15-rc3.x
linux / linux_kernel 6.15-rc4 6.15-rc4.x
linux / linux_kernel 6.15-rc5 6.15-rc5.x
linux / linux_kernel 6.15-rc6 6.15-rc6.x