Toshiaki Makita
2014-Nov-06 07:07 UTC
[Bridge] [PATCH] bridge: missing null bridge device check causing null pointer dereference (bugfix)
On 2014/11/06 15:26, Su-Hyun Park wrote:> the bridge device can be null if the bridge is being deleted while processing > the packet, which causes the null pointer dereference in switch statement.How can this happen?? It is guarded by rcu. netdev_rx_handler_unregister() ensures rx_handler_data is non NULL. Thanks, Toshiaki Makita> > crash dump snippet: > > <1>BUG: unable to handle kernel NULL pointer dereference at 0000000000000021 > <1>IP: [<ffffffff814179f6>] br_handle_frame+0xe6/0x270 > > <0>Code: 4c 0f 44 f0 89 f8 66 33 15 32 52 24 00 66 33 05 29 52 24 00 09 c2 89 > f0 66 33 05 22 52 24 00 80 e4 f0 66 09 c2 0f 84 eb 00 00 00 <41> 0f b6 46 21 > 3c 02 74 61 3c 03 74 1d 48 89 df e8 d5 bc f0 ff > --- > net/bridge/br_input.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c > index 6fd5522..7e899ca 100644 > --- a/net/bridge/br_input.c > +++ b/net/bridge/br_input.c > @@ -176,6 +176,8 @@ rx_handler_result_t br_handle_frame(struct sk_buff **pskb) > return RX_HANDLER_CONSUMED; > > p = br_port_get_rcu(skb->dev); > + if (!p) > + goto drop; > > if (unlikely(is_link_local_ether_addr(dest))) { > u16 fwd_mask = p->br->group_fwd_mask_required; >