linux/include
Jiri Pirko f2f17ef7c7 macvlan: fix passthru mode race between dev removal and rx path
[ Upstream commit 233c7df082, note
  that I had to add list_first_or_null_rcu to rculist.h in order
  to accomodate this fix. ]

Currently, if macvlan in passthru mode is created and data are rxed and
you remove this device, following panic happens:

NULL pointer dereference at 0000000000000198
IP: [<ffffffffa0196058>] macvlan_handle_frame+0x153/0x1f7 [macvlan]

I'm using following script to trigger this:
<script>
while [ 1 ]
do
	ip link add link e1 name macvtap0 type macvtap mode passthru
	ip link set e1 up
	ip link set macvtap0 up
	IFINDEX=`ip link |grep macvtap0 | cut -f 1 -d ':'`
	cat /dev/tap$IFINDEX  >/dev/null &
	ip link del dev macvtap0
done
</script>

I run this script while "ping -f" is running on another machine to send
packets to e1 rx.

Reason of the panic is that list_first_entry() is blindly called in
macvlan_handle_frame() even if the list was empty. vlan is set to
incorrect pointer which leads to the crash.

I'm fixing this by protecting port->vlans list by rcu and by preventing
from getting incorrect pointer in case the list is empty.

Introduced by: commit eb06acdc85 "macvlan: Introduce 'passthru' mode to takeover the underlying device"

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-05-19 10:54:47 -07:00
..
acpi Merge branch 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux 2012-05-05 10:06:06 -07:00
asm-generic mm: allow arch code to control the user page table ceiling 2013-05-07 19:51:55 -07:00
crypto crypto: user - Fix lookup of algorithms with IV generator 2012-03-29 19:52:47 +08:00
drm drm/radeon: add new richland pci ids 2013-05-11 13:48:14 -07:00
keys
linux macvlan: fix passthru mode race between dev removal and rx path 2013-05-19 10:54:47 -07:00
math-emu
media Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2012-05-14 11:23:37 -07:00
misc
mtd
net tcp: force a dst refcount when prequeue packet 2013-05-19 10:54:43 -07:00
pcmcia
rdma infiniband: pass rdma_cm module to netlink_dump_start 2012-10-28 10:14:15 -07:00
rxrpc
scsi SCSI: libsas: fix taskfile corruption in sas_ata_qc_fill_rtf 2012-07-16 09:04:37 -07:00
sound ALSA: Add a reference counter to card instance 2012-11-17 13:16:13 -08:00
target target: Add link_magic for fabric allow_link destination target_items 2013-01-21 11:45:24 -08:00
trace xen/mmu: Use Xen specific TLB flush instead of the generic one. 2012-11-17 13:15:54 -08:00
video atmel_lcdfb: fix 16-bpp modes on older SOCs 2013-03-20 13:05:00 -07:00
xen xen/blkback: correctly respond to unknown, non-native requests 2013-04-05 10:04:18 -07:00
Kbuild