diff options
author | Jiri Pirko <jiri@resnulli.us> | 2013-05-09 04:23:40 +0000 |
---|---|---|
committer | Ben Hutchings <ben@decadent.org.uk> | 2013-05-30 14:35:14 +0100 |
commit | 24ac9e8939ffcbfed67eea6e82c7eb99c34d0b55 (patch) | |
tree | bc6cadf214a67ba8e8fbb3d6ddd78876fe5d818a /include/linux/rculist.h | |
parent | 00c76e26b7e25c4f0790b9d4d54253cbf24dce1b (diff) |
macvlan: fix passthru mode race between dev removal and rx path
[ Upstream commit 233c7df0821c4190e2d3f4be0f2ca0ab40a5ed8c, 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 eb06acdc85585f2 "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: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'include/linux/rculist.h')
-rw-r--r-- | include/linux/rculist.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/rculist.h b/include/linux/rculist.h index d079290843a9..6f95e241ed68 100644 --- a/include/linux/rculist.h +++ b/include/linux/rculist.h @@ -242,6 +242,23 @@ static inline void list_splice_init_rcu(struct list_head *list, list_entry_rcu((ptr)->next, type, member) /** + * list_first_or_null_rcu - get the first element from a list + * @ptr: the list head to take the element from. + * @type: the type of the struct this is embedded in. + * @member: the name of the list_struct within the struct. + * + * Note that if the list is empty, it returns NULL. + * + * This primitive may safely run concurrently with the _rcu list-mutation + * primitives such as list_add_rcu() as long as it's guarded by rcu_read_lock(). + */ +#define list_first_or_null_rcu(ptr, type, member) \ + ({struct list_head *__ptr = (ptr); \ + struct list_head __rcu *__next = list_next_rcu(__ptr); \ + likely(__ptr != __next) ? container_of(__next, type, member) : NULL; \ + }) + +/** * list_for_each_entry_rcu - iterate over rcu list of given type * @pos: the type * to use as a loop cursor. * @head: the head for your list. |