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Date:      Mon, 13 Jan 2020 16:08:50 +0000
From:      bugzilla-noreply@freebsd.org
To:        bugs@FreeBSD.org
Subject:   [Bug 243324] Module with 'mii' can panic during kldunload
Message-ID:  <bug-243324-227@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D243324

            Bug ID: 243324
           Summary: Module with 'mii' can panic during kldunload
           Product: Base System
           Version: CURRENT
          Hardware: Any
                OS: Any
            Status: New
          Severity: Affects Many People
          Priority: ---
         Component: kern
          Assignee: bugs@FreeBSD.org
          Reporter: ghuckriede@blackberry.com

Overview:
While trying to see if setting ivars to NULL during detach was required (See
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D242727), discovered 're'
module can panic on kldunload.  Upon further analysis, it was determined th=
at
there is no protection for ioctls during the kldunload.  The 'mii' devices
appear to be detached and destroyed while ioctl (ifconfig) is holding the
RL_LOCK.  There does not appear to be a 'mii' device lock (perhaps assuming=
 the
RL_LOCK would protect it, which it doesn't).

Steps to Reproduce:
Compile a kernel without re module (needed to do a kldunload).


After rebooting open 2 terminals (ssh for example)
for 're'
#### 1st terminal
$ su root
# /bin/sh
# while true ; do kldload
/usr/obj/usr/src/amd64.amd64/sys/modules/re/if_re.ko;ifconfig re0 up;sleep =
1;
kldunload if_re.ko ; done

#### 2nd terminal
$ su root
# /bin/sh
# while true ; do ifconfig re0 ; done

OR for 'axe'
$ su root
# /bin/sh
# while true ; do ifconfig ue0 up;sleep 1; kldunload if_axe.ko ; done

#### 2nd terminal
$ su root
# /bin/sh
# while true ; do ifconfig ue0 ; done


Actual Results:
Panic occurred within a few seconds.

Expected Results:
no panic

Build Date & Hardware:

# uname -a
FreeBSD FreeBSD_head_ghuckriede 13.0-CURRENT FreeBSD 13.0-CURRENT #2 r35655=
9:
Thu Jan  9 15:45:41 EST 2020=20=20=20=20
ghuckriede@FreeBSD_head_ghuckriede:/usr/obj/usr/src/amd64.amd64/sys/GENERIC=
_NO_RE
 amd64

--=20
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