From: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx>
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:[<ffffffffa059035e>] [<ffffffffa059035e>]
nft_limit_pkt_bytes_eval+0x2e/0xa0 [nft_limit]
Call Trace:
[<ffffffffa05721bb>] nft_do_chain+0xfb/0x4e0 [nf_tables]
[<ffffffffa044f236>] ? nf_nat_setup_info+0x96/0x480 [nf_nat]
[<ffffffff81753767>] ? ipt_do_table+0x327/0x610
[<ffffffffa044f677>] ? __nf_nat_alloc_null_binding+0x57/0x80 [nf_nat]
[<ffffffffa058b21f>] nft_ipv4_output+0xaf/0xd0 [nf_tables_ipv4]
[<ffffffff816f4aa2>] nf_iterate+0x62/0x80
[<ffffffff816f4b33>] nf_hook_slow+0x73/0xd0
[<ffffffff81703d0d>] __ip_local_out+0xcd/0xe0
[<ffffffff81701d90>] ? ip_forward_options+0x1b0/0x1b0
[<ffffffff81703d3c>] 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 <liping.zhang@xxxxxxxxxxxxxx>
---
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 070b989..c6baf41 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;
--
2.5.5
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