Date: Mon, 23 Dec 2019 20:08:45 +0000 From: bugzilla-noreply@freebsd.org To: bugs@FreeBSD.org Subject: [Bug 242841] Unkillable process when attempting to destroy an open tun device Message-ID: <bug-242841-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D242841 Bug ID: 242841 Summary: Unkillable process when attempting to destroy an open tun device Product: Base System Version: 12.1-RELEASE Hardware: Any OS: Any Status: New Severity: Affects Only Me Priority: --- Component: kern Assignee: bugs@FreeBSD.org Reporter: cperciva@FreeBSD.org This is admittedly partly a case of "don't do that" (I tripped over it due = to a bug in code I was writing), but it seems like the kernel should handle it a= bit more gracefully. If you: 1. Create a tun device (via SIOCIFCREATE), 2. Open the tun device (via open("/dev/tun#")), and then 3. Attempt to destroy the tun device (via SIOCIFDESTROY), the SIOCIFDESTROY ioctl will block on tun_condvar until the last file descriptor holding the device open has been closed. Generally sensible... except that the file descriptor in question is owned by the process which called the ioctl, and it's stuck inside the kernel now and will never be ab= le to close the device. This results in a process which cannot be killed. A better solution might be to detect when the process calling SIOCIFDESTROY= is the same as the process which owns the tunnel device, and return an error (maybe EBUSY) rather than blocking indefinitely. --=20 You are receiving this mail because: You are the assignee for the bug.=
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