Wind River Support Network

Description

In the Linux kernel, the following vulnerability has been resolved:  net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled  When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference.   BUG: kernel NULL pointer dereference, address: 0000000000000268  Oops: 0000 [#1] PREEMPT SMP NOPTI  [...]  RIP: 0010:neigh_lookup+0x16/0xe0  [...]  Call Trace:   <IRQ>   ? neigh_lookup+0x16/0xe0   br_do_suppress_nd+0x160/0x290 [bridge]   br_handle_frame_finish+0x500/0x620 [bridge]   br_handle_frame+0x353/0x440 [bridge]   __netif_receive_skb_core.constprop.0+0x298/0x1110   __netif_receive_skb_one_core+0x3d/0xa0   process_backlog+0xa0/0x140   __napi_poll+0x2c/0x170   net_rx_action+0x2c4/0x3a0   handle_softirqs+0xd0/0x270   do_softirq+0x3f/0x60  Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled.