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authorFlorian Westphal <fw@strlen.de>2019-10-29 01:44:04 +0100
committerDavid S. Miller <davem@davemloft.net>2019-10-29 17:54:29 -0700
commit51210ad5a558dcc7511d0c083f5cd796077b4e4d (patch)
tree50f32514dcef0f73374301a8044e6f976d5645df /net/ipv4/ip_input.c
parentacda6180e86ba9e0026287d65f30d1e2b0c8882a (diff)
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inet: do not call sublist_rcv on empty list
syzbot triggered struct net NULL deref in NF_HOOK_LIST: RIP: 0010:NF_HOOK_LIST include/linux/netfilter.h:331 [inline] RIP: 0010:ip6_sublist_rcv+0x5c9/0x930 net/ipv6/ip6_input.c:292 ipv6_list_rcv+0x373/0x4b0 net/ipv6/ip6_input.c:328 __netif_receive_skb_list_ptype net/core/dev.c:5274 [inline] Reason: void ipv6_list_rcv(struct list_head *head, struct packet_type *pt, struct net_device *orig_dev) [..] list_for_each_entry_safe(skb, next, head, list) { /* iterates list */ skb = ip6_rcv_core(skb, dev, net); /* ip6_rcv_core drops skb -> NULL is returned */ if (skb == NULL) continue; [..] } /* sublist is empty -> curr_net is NULL */ ip6_sublist_rcv(&sublist, curr_dev, curr_net); Before the recent change NF_HOOK_LIST did a list iteration before struct net deref, i.e. it was a no-op in the empty list case. List iteration now happens after *net deref, causing crash. Follow the same pattern as the ip(v6)_list_rcv loop and add a list_empty test for the final sublist dispatch too. Cc: Edward Cree <ecree@solarflare.com> Reported-by: syzbot+c54f457cad330e57e967@syzkaller.appspotmail.com Fixes: ca58fbe06c54 ("netfilter: add and use nf_hook_slow_list()") Signed-off-by: Florian Westphal <fw@strlen.de> Tested-by: Leon Romanovsky <leonro@mellanox.com> Tested-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv4/ip_input.c')
-rw-r--r--net/ipv4/ip_input.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/ip_input.c b/net/ipv4/ip_input.c
index c59a78a267c3..24a95126e698 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -611,5 +611,6 @@ void ip_list_rcv(struct list_head *head, struct packet_type *pt,
list_add_tail(&skb->list, &sublist);
}
/* dispatch final sublist */
- ip_sublist_rcv(&sublist, curr_dev, curr_net);
+ if (!list_empty(&sublist))
+ ip_sublist_rcv(&sublist, curr_dev, curr_net);
}