From 2fa46c130193300f06e68727ae98ec9f6184cad4 Mon Sep 17 00:00:00 2001 From: Liping Zhang Date: Tue, 27 Sep 2016 20:49:19 +0800 Subject: [PATCH] netfilter: nft_limit: fix divided by zero panic After I input the following nftables rule, a panic happened on my system: # nft add rule filter OUTPUT limit rate 0xf00000000 bytes/second divide error: 0000 [#1] SMP [ ... ] RIP: 0010:[] [] nft_limit_pkt_bytes_eval+0x2e/0xa0 [nft_limit] Call Trace: [] nft_do_chain+0xfb/0x4e0 [nf_tables] [] ? nf_nat_setup_info+0x96/0x480 [nf_nat] [] ? ipt_do_table+0x327/0x610 [] ? __nf_nat_alloc_null_binding+0x57/0x80 [nf_nat] [] nft_ipv4_output+0xaf/0xd0 [nf_tables_ipv4] [] nf_iterate+0x62/0x80 [] nf_hook_slow+0x73/0xd0 [] __ip_local_out+0xcd/0xe0 [] ? ip_forward_options+0x1b0/0x1b0 [] ip_local_out+0x1c/0x40 This is because divisor is 64-bit, but we treat it as a 32-bit integer, then 0xf00000000 becomes zero, i.e. divisor becomes 0. Signed-off-by: Liping Zhang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_limit.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netfilter/nft_limit.c b/net/netfilter/nft_limit.c index 070b98938e02..c6baf412236d 100644 --- a/net/netfilter/nft_limit.c +++ b/net/netfilter/nft_limit.c @@ -145,7 +145,7 @@ static int nft_limit_pkts_init(const struct nft_ctx *ctx, if (err < 0) return err; - priv->cost = div_u64(priv->limit.nsecs, priv->limit.rate); + priv->cost = div64_u64(priv->limit.nsecs, priv->limit.rate); return 0; } @@ -170,7 +170,7 @@ static void nft_limit_pkt_bytes_eval(const struct nft_expr *expr, const struct nft_pktinfo *pkt) { struct nft_limit *priv = nft_expr_priv(expr); - u64 cost = div_u64(priv->nsecs * pkt->skb->len, priv->rate); + u64 cost = div64_u64(priv->nsecs * pkt->skb->len, priv->rate); if (nft_limit_eval(priv, cost)) regs->verdict.code = NFT_BREAK; -- 2.11.0