linux/include
Linus Torvalds 698b368275 fbcon: add lifetime refcount to opened frame buffers
This just adds the refcount and the new registration lock logic.  It
does not (for example) actually change the read/write/ioctl routines to
actually use the frame buffer that was opened: those function still end
up alway susing whatever the current frame buffer is at the time of the
call.

Without this, if something holds the frame buffer open over a
framebuffer switch, the close() operation after the switch will access a
fb_info that has been free'd by the unregistering of the old frame
buffer.

(The read/write/ioctl operations will normally not cause problems,
because they will - illogically - pick up the new fbcon instead.  But a
switch that happens just as one of those is going on might see problems
too, the window is just much smaller: one individual op rather than the
whole open-close sequence.)

This use-after-free is apparently fairly easily triggered by the Ubuntu
11.04 boot sequence.

Acked-by: Tim Gardner <tim.gardner@canonical.com>
Tested-by: Daniel J Blueman <daniel.blueman@gmail.com>
Tested-by: Anca Emanuel <anca.emanuel@gmail.com>
Cc: Bruno Prémont <bonbons@linux-vserver.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Dave Airlie <airlied@redhat.com>
Cc: Andy Whitcroft <andy.whitcroft@canonical.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-05-12 07:37:51 -07:00
..
acpi Fix common misspellings 2011-03-31 11:26:23 -03:00
asm-generic Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
crypto
drm drm: mm: fix debug output 2011-05-09 09:14:45 +10:00
keys libceph: Create a new key type "ceph". 2011-03-29 12:11:24 -07:00
linux fbcon: add lifetime refcount to opened frame buffers 2011-05-12 07:37:51 -07:00
math-emu
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6 2011-04-27 15:17:52 -07:00
mtd
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6 2011-05-10 17:39:01 -07:00
pcmcia
rdma
rxrpc Fix common misspellings 2011-03-31 11:26:23 -03:00
scsi Fix common misspellings 2011-03-31 11:26:23 -03:00
sound Merge branch 'for-linus2' of git://git.profusion.mobi/users/lucas/linux-2.6 2011-04-07 11:14:49 -07:00
staging [media] Altera FPGA firmware download module 2011-03-21 20:32:16 -03:00
target Fix common misspellings 2011-03-31 11:26:23 -03:00
trace block: make unplug timer trace event correspond to the schedule() unplug 2011-04-16 13:51:05 +02:00
video Fix common misspellings 2011-03-31 11:26:23 -03:00
xen Fix common misspellings 2011-03-31 11:26:23 -03:00
Kbuild