From ce46cc64d47a8afaf13c300b09a7f9c29f4979b6 Mon Sep 17 00:00:00 2001 From: Shan Wei Date: Tue, 4 Dec 2012 18:49:15 +0000 Subject: [PATCH] net: neighbour: prohibit negative value for unres_qlen_bytes parameter MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit unres_qlen_bytes and unres_qlen are int type. But multiple relation(unres_qlen_bytes = unres_qlen * SKB_TRUESIZE(ETH_FRAME_LEN)) will cause type overflow when seting unres_qlen. e.g. $ echo 1027506 > /proc/sys/net/ipv4/neigh/eth1/unres_qlen $ cat /proc/sys/net/ipv4/neigh/eth1/unres_qlen 1182657265 $ cat /proc/sys/net/ipv4/neigh/eth1/unres_qlen_bytes -2147479756 The gutted value is not that we setting。 But user/administrator don't know this is caused by int type overflow. what's more, it is meaningless and even dangerous that unres_qlen_bytes is set with negative number. Because, for unresolved neighbour address, kernel will cache packets without limit in __neigh_event_send()(e.g. (u32)-1 = 2GB). Signed-off-by: Shan Wei Signed-off-by: David S. Miller --- net/core/neighbour.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/net/core/neighbour.c b/net/core/neighbour.c index f1c0c2e9cad5..36fc692e2bde 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -62,6 +62,9 @@ static void __neigh_notify(struct neighbour *n, int type, int flags); static void neigh_update_notify(struct neighbour *neigh); static int pneigh_ifdown(struct neigh_table *tbl, struct net_device *dev); +static int zero; +static int unres_qlen_max = INT_MAX / SKB_TRUESIZE(ETH_FRAME_LEN); + static struct neigh_table *neigh_tables; #ifdef CONFIG_PROC_FS static const struct file_operations neigh_stat_seq_fops; @@ -1787,8 +1790,7 @@ static int neightbl_fill_parms(struct sk_buff *skb, struct neigh_parms *parms) nla_put_u32(skb, NDTPA_QUEUE_LENBYTES, parms->queue_len_bytes) || /* approximative value for deprecated QUEUE_LEN (in packets) */ nla_put_u32(skb, NDTPA_QUEUE_LEN, - DIV_ROUND_UP(parms->queue_len_bytes, - SKB_TRUESIZE(ETH_FRAME_LEN))) || + parms->queue_len_bytes / SKB_TRUESIZE(ETH_FRAME_LEN)) || nla_put_u32(skb, NDTPA_PROXY_QLEN, parms->proxy_qlen) || nla_put_u32(skb, NDTPA_APP_PROBES, parms->app_probes) || nla_put_u32(skb, NDTPA_UCAST_PROBES, parms->ucast_probes) || @@ -2777,9 +2779,13 @@ static int proc_unres_qlen(ctl_table *ctl, int write, void __user *buffer, int size, ret; ctl_table tmp = *ctl; + tmp.extra1 = &zero; + tmp.extra2 = &unres_qlen_max; tmp.data = &size; - size = DIV_ROUND_UP(*(int *)ctl->data, SKB_TRUESIZE(ETH_FRAME_LEN)); - ret = proc_dointvec(&tmp, write, buffer, lenp, ppos); + + size = *(int *)ctl->data / SKB_TRUESIZE(ETH_FRAME_LEN); + ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos); + if (write && !ret) *(int *)ctl->data = size * SKB_TRUESIZE(ETH_FRAME_LEN); return ret; @@ -2865,7 +2871,8 @@ static struct neigh_sysctl_table { .procname = "unres_qlen_bytes", .maxlen = sizeof(int), .mode = 0644, - .proc_handler = proc_dointvec, + .extra1 = &zero, + .proc_handler = proc_dointvec_minmax, }, [NEIGH_VAR_PROXY_QLEN] = { .procname = "proxy_qlen", -- 2.20.1