Submission + - And another Linux vunerablity, SSH private keys. (github.com)
mrspoonsi writes: Steal SSH host private keys and /etc/shadow via the ptrace_may_access mm-NULL bypass + pidfd_getfd. Pre-31e62c2ebbfd kernels.
__ptrace_may_access() skips the dumpable check when task->mm == NULL. do_exit() runs exit_mm() before exit_files() — no mm, fds still there. pidfd_getfd(2) succeeds in that window when the caller's uid matches the target's.
Reported by Qualys, fixed by Linus 2026-05-14. Jann Horn flagged the FD-theft shape in October 2020.
__ptrace_may_access() skips the dumpable check when task->mm == NULL. do_exit() runs exit_mm() before exit_files() — no mm, fds still there. pidfd_getfd(2) succeeds in that window when the caller's uid matches the target's.
Reported by Qualys, fixed by Linus 2026-05-14. Jann Horn flagged the FD-theft shape in October 2020.