Commit a533b70a authored by weichenchen's avatar weichenchen Committed by David S. Miller
Browse files

net: neighbor: fix a crash caused by mod zero 



pneigh_enqueue() tries to obtain a random delay by mod
NEIGH_VAR(p, PROXY_DELAY). However, NEIGH_VAR(p, PROXY_DELAY)
migth be zero at that point because someone could write zero
to /proc/sys/net/ipv4/neigh/[device]/proxy_delay after the
callers check it.

This patch uses prandom_u32_max() to get a random delay instead
which avoids potential division by zero.

Signed-off-by: default avatarweichenchen <weichen.chen@linux.alibaba.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 21fdca22

net/core/neighbour.c

+2 −4
Original line number Diff line number Diff line
@@ -1569,10 +1569,8 @@ static void neigh_proxy_process(struct timer_list *t) 
void pneigh_enqueue(struct neigh_table *tbl, struct neigh_parms *p,

		    struct sk_buff *skb)

{

	unsigned long now = jiffies;



	unsigned long sched_next = now + (prandom_u32() %

					  NEIGH_VAR(p, PROXY_DELAY));

	unsigned long sched_next = jiffies +

			prandom_u32_max(NEIGH_VAR(p, PROXY_DELAY));



	if (tbl->proxy_queue.qlen > NEIGH_VAR(p, PROXY_QLEN)) {

		kfree_skb(skb);