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[Bug 1165433] Re: Kernel 3.8.x panics on bluetooth DUN disconnect


I read it as destroying the tty structure before it was completely
cleaned up, so future references to the tty struct were pointing to
freed memory.   Even better it looks like a new version of the patch set
was released today Jul 26, in fact just now pretty much, subject
"rfcomm: Implement rfcomm as a proper tty_port" where Gianluca writes:

"This patchset addresses an issue with the rfcomm tty driver in the
current stable kernels that manifests itself as a sudden lockup of the
whole machine or as a OOPS if we are lucky enough (I wasn't).

Triggering the problem is very easy:

1) establish a bluetooth connection with a bluetooth host
2) open the tty it provides with some program
3) turn off the bluetooth host or take it out of range"

which sounds very much like the problem we're seeing.

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  Kernel 3.8.x panics on bluetooth DUN disconnect

Status in “linux” package in Ubuntu:

Bug description:
  Issue is obviously in the kernel that should not panic in any circumnstances.
  This bug is seen on quantal using the kernel from PPA mainline. Tested with 3.8.0 to 3.8.6.
  Since 3.8.x is going to be the raring kernel I believe that this should definitely be fixed before raring is shipped.

  Seen on:

  DELL E6500 with kubuntu quantal 12.10 64 bit and as said, kernel 3.8.6 from the mainline ppa.
  The machine has a Dell Computer Corp. Wireless 370 Bluetooth Mini-card (connected via an internal usb connection).

  The issue is shown when connecting to the internet via a Samsung Galaxy S plus phone, using a bluetooth DUN connection.
  It is reproducible every time.

  How to reproduce:

  1) Use the bluetooth applet to discover the phone and associate to it.
  2) Use network manager to setup a DUN connection with the phone through your APN
  3) Connect to the internet via bluetooth DUN (connection works perfectly)
  4) Disconnect from the network manager.

  At the same time you disconnect, the GUI session is terminated and the
  kernel panics, briefly showing a panic log on the screen.

  Note that:

  a) The issue is not present using the standard ubuntu quantal kernel
  b) The issue is not present using kernels from the mainline ppa before 3.8 (e.g., 3.7.x is fine for all x)
  c) The issue is not present when connecting to the internet using a USB mobile dongle (e.g. Huawei usb key)

  This looks pretty serious to me: kernel does not sync when panicing
  and there is a serious risk of data loss; connecting to the internet
  via a smart phone using bluetooth DUN seems to be something that one
  should take for granted on any modern OS. Furthermore, points a) and
  b) above show that this is a *regression* over previous kernels.

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