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ila: Fix crash caused by rhashtable changes

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commit ca26893f05e86 ("rhashtable: Add rhlist interface")
added a field to rhashtable_iter so that length became 56 bytes
and would exceed the size of args in netlink_callback (which is
48 bytes). The netlink diag dump function already has been
allocating a iter structure and storing the pointed to that
in the args of netlink_callback. ila_xlat also uses
rhahstable_iter but is still putting that directly in
the arg block. Now since rhashtable_iter size is increased
we are overwriting beyond the structure. The next field
happens to be cb_mutex pointer in netlink_sock and hence the crash.

Fix is to alloc the rhashtable_iter and save it as pointer
in arg.

Tested:

  modprobe ila
  ./ip ila add loc 3333:0:0:0 loc_match 2222:0:0:1,
  ./ip ila list  # NO crash now

Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Tom Herbert 2016-11-01 14:55:25 -07:00 committed by David S. Miller
parent 3de864f8c9
commit 1913540a13
1 changed files with 13 additions and 3 deletions
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16
net/ipv6/ila/ila_xlat.c
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@ -474,7 +474,15 @@ static int ila_nl_dump_start(struct netlink_callback *cb)
{
struct net *net = sock_net(cb->skb->sk);
struct ila_net *ilan = net_generic(net, ila_net_id);
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args;
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args[0];
if (!iter) {
iter = kmalloc(sizeof(*iter), GFP_KERNEL);
if (!iter)
return -ENOMEM;
cb->args[0] = (long)iter;
}
return rhashtable_walk_init(&ilan->rhash_table, &iter->rhiter,
GFP_KERNEL);
@ -482,16 +490,18 @@ static int ila_nl_dump_start(struct netlink_callback *cb)
static int ila_nl_dump_done(struct netlink_callback *cb)
{
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args;
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args[0];
rhashtable_walk_exit(&iter->rhiter);
kfree(iter);
return 0;
}
static int ila_nl_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args;
struct ila_dump_iter *iter = (struct ila_dump_iter *)cb->args[0];
struct rhashtable_iter *rhiter = &iter->rhiter;
struct ila_map *ila;
int ret;