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From 6def05e2e3014f0edecd1dfbac15d5776c357a04 Mon Sep 17 00:00:00 2001
From: Sasha Levin <sashal@kernel.org>
Date: Sat, 20 Apr 2024 07:01:16 +0000
Subject: icmp: prevent possible NULL dereferences from icmp_build_probe()
From: Eric Dumazet <edumazet@google.com>
[ Upstream commit c58e88d49097bd12dfcfef4f075b43f5d5830941 ]
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: d329ea5bd884 ("icmp: add response to RFC 8335 PROBE messages")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Andreas Roeseler <andreas.a.roeseler@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/icmp.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)
diff --git a/net/ipv4/icmp.c b/net/ipv4/icmp.c
index 2b09ef70752f9..31051b327e53c 100644
--- a/net/ipv4/icmp.c
+++ b/net/ipv4/icmp.c
@@ -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
@@ -1029,6 +1030,8 @@ 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;
@@ -1112,10 +1115,15 @@ 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;
--
2.43.0
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