From 1913540a1328d70edf8597f6c2248575d9d2ad62 Mon Sep 17 00:00:00 2001 From: Tom Herbert Date: Tue, 1 Nov 2016 14:55:25 -0700 Subject: [PATCH] ila: Fix crash caused by rhashtable changes 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 Signed-off-by: David S. Miller --- net/ipv6/ila/ila_xlat.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/net/ipv6/ila/ila_xlat.c b/net/ipv6/ila/ila_xlat.c index 628ae6d..af8f52e 100644 --- a/net/ipv6/ila/ila_xlat.c +++ b/net/ipv6/ila/ila_xlat.c @@ -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; -- 2.7.4