Commit c58e88d4 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

icmp: prevent possible NULL dereferences from icmp_build_probe() 



First problem is a double call to __in_dev_get_rcu(), because
the second one could return NULL.

if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)

Second problem is a read from dev->ip6_ptr with no NULL check:

if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))

Use the correct RCU API to fix these.

v2: add missing include <net/addrconf.h>

Fixes: d329ea5b ("icmp: add response to RFC 8335 PROBE messages")
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Cc: Andreas Roeseler <andreas.a.roeseler@gmail.com>
Reviewed-by: default avatarDavid Ahern <dsahern@kernel.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0b8fe5bd

net/ipv4/icmp.c

+10 −2
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ 
#include <net/inet_common.h>

#include <net/ip_fib.h>

#include <net/l3mdev.h>

#include <net/addrconf.h>



/*

 *	Build xmit assembly blocks
@@ -1032,6 +1033,8 @@ bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 
	struct icmp_ext_hdr *ext_hdr, _ext_hdr;

	struct icmp_ext_echo_iio *iio, _iio;

	struct net *net = dev_net(skb->dev);

	struct inet6_dev *in6_dev;

	struct in_device *in_dev;

	struct net_device *dev;

	char buff[IFNAMSIZ];

	u16 ident_len;
@@ -1115,10 +1118,15 @@ bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr) 
	/* Fill bits in reply message */

	if (dev->flags & IFF_UP)

		status |= ICMP_EXT_ECHOREPLY_ACTIVE;

	if (__in_dev_get_rcu(dev) && __in_dev_get_rcu(dev)->ifa_list)



	in_dev = __in_dev_get_rcu(dev);

	if (in_dev && rcu_access_pointer(in_dev->ifa_list))

		status |= ICMP_EXT_ECHOREPLY_IPV4;

	if (!list_empty(&rcu_dereference(dev->ip6_ptr)->addr_list))



	in6_dev = __in6_dev_get(dev);

	if (in6_dev && !list_empty(&in6_dev->addr_list))

		status |= ICMP_EXT_ECHOREPLY_IPV6;



	dev_put(dev);

	icmphdr->un.echo.sequence |= htons(status);

	return true;