From: Chen Zhongjin chenzhongjin@huawei.com
[ Upstream commit f8017317cb0b279b8ab98b0f3901a2e0ac880dad ]
When IPv6 module gets initialized but hits an error in the middle, kenel panic with:
KASAN: null-ptr-deref in range [0x0000000000000598-0x000000000000059f] CPU: 1 PID: 361 Comm: insmod Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:__neigh_ifdown.isra.0+0x24b/0x370 RSP: 0018:ffff888012677908 EFLAGS: 00000202 ... Call Trace: <TASK> neigh_table_clear+0x94/0x2d0 ndisc_cleanup+0x27/0x40 [ipv6] inet6_init+0x21c/0x2cb [ipv6] do_one_initcall+0xd3/0x4d0 do_init_module+0x1ae/0x670 ... Kernel panic - not syncing: Fatal exception
When ipv6 initialization fails, it will try to cleanup and calls:
neigh_table_clear() neigh_ifdown(tbl, NULL) pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev == NULL)) # dev_net(NULL) triggers null-ptr-deref.
Fix it by passing NULL to pneigh_queue_purge() in neigh_ifdown() if dev is NULL, to make kernel not panic immediately.
Fixes: 66ba215cb513 ("neigh: fix possible DoS due to net iface start/stop loop") Signed-off-by: Chen Zhongjin chenzhongjin@huawei.com Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: Denis V. Lunev den@openvz.org Link: https://lore.kernel.org/r/20221101121552.21890-1-chenzhongjin@huawei.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/neighbour.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 78cc8fb68814..84755db81e9d 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -409,7 +409,7 @@ static int __neigh_ifdown(struct neigh_table *tbl, struct net_device *dev, write_lock_bh(&tbl->lock); neigh_flush_dev(tbl, dev, skip_perm); pneigh_ifdown_and_unlock(tbl, dev); - pneigh_queue_purge(&tbl->proxy_queue, dev_net(dev)); + pneigh_queue_purge(&tbl->proxy_queue, dev ? dev_net(dev) : NULL); if (skb_queue_empty_lockless(&tbl->proxy_queue)) del_timer_sync(&tbl->proxy_timer); return 0;