netfilter: h323: avoid potential attack

PATCH Superseded Zhouyi Zhou 1 participant 1 message Jan 28, 2016

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Zhouyi Zhou

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2016-01-28 09:34 UTC #0 lore raw

PATCH v2 1/1 netfilter: h323: avoid potential attack

Thanks Eric for your review and advice.

I think hackers chould build a malicious h323 packet to overflow the pointer p which will panic during the memcpy(addr, p, len)

For example, he may fabricate a very large taddr->ipAddress.ip;

Signed-off-by Zhouyi Zhou <[email protected]>

---
 net/netfilter/nf_conntrack_h323_main.c |    7 +++++++
 1 file changed, 7 insertions(+)

net/netfilter/nf_conntrack_h323_main.c +7 -0

index 9511af0..ccd08c5 100644
@@ -110,6 +110,7 @@ int (*nat_q931_hook) (struct sk_buff *skb,
 
 static DEFINE_SPINLOCK(nf_h323_lock);
 static char *h323_buffer;
+#define CHECK_BOUND(p, n) ((void *)p + n - (void *)h323_buffer > 65536)
 
 static struct nf_conntrack_helper nf_conntrack_helper_h245;
 static struct nf_conntrack_helper nf_conntrack_helper_q931[];

@@ -247,6 +248,9 @@ static int get_h245_addr(struct nf_conn *ct, const unsigned char *data,
 		return 0;
 	}
 
+	if (CHECK_BOUND(p, len + sizeof(__be16)))
+		return 0;
+
 	memcpy(addr, p, len);
 	memset((void *)addr + len, 0, sizeof(*addr) - len);
 	memcpy(port, p + len, sizeof(__be16));

@@ -669,6 +673,9 @@ int get_h225_addr(struct nf_conn *ct, unsigned char *data,
 		return 0;
 	}
 
+	if (CHECK_BOUND(p, len + sizeof(__be16)))
+		return 0;
+
 	memcpy(addr, p, len);
 	memset((void *)addr + len, 0, sizeof(*addr) - len);
 	memcpy(port, p + len, sizeof(__be16));

Signature · 1 line

1.7.10.4