From fcbdf09d9652c8919dcf47072e3ae7dcb4eb98ac Mon Sep 17 00:00:00 2001
From: Octavian Purdila <opurdila@ixiacom.com>
Date: Thu, 16 Dec 2010 14:26:56 -0800
Subject: net: fix nulls list corruptions in sk_prot_alloc

Special care is taken inside sk_port_alloc to avoid overwriting
skc_node/skc_nulls_node. We should also avoid overwriting
skc_bind_node/skc_portaddr_node.

The patch fixes the following crash:

 BUG: unable to handle kernel paging request at fffffffffffffff0
 IP: [<ffffffff812ec6dd>] udp4_lib_lookup2+0xad/0x370
 [<ffffffff812ecc22>] __udp4_lib_lookup+0x282/0x360
 [<ffffffff812ed63e>] __udp4_lib_rcv+0x31e/0x700
 [<ffffffff812bba45>] ? ip_local_deliver_finish+0x65/0x190
 [<ffffffff812bbbf8>] ? ip_local_deliver+0x88/0xa0
 [<ffffffff812eda35>] udp_rcv+0x15/0x20
 [<ffffffff812bba45>] ip_local_deliver_finish+0x65/0x190
 [<ffffffff812bbbf8>] ip_local_deliver+0x88/0xa0
 [<ffffffff812bb2cd>] ip_rcv_finish+0x32d/0x6f0
 [<ffffffff8128c14c>] ? netif_receive_skb+0x99c/0x11c0
 [<ffffffff812bb94b>] ip_rcv+0x2bb/0x350
 [<ffffffff8128c14c>] netif_receive_skb+0x99c/0x11c0

Signed-off-by: Leonard Crestez <lcrestez@ixiacom.com>
Signed-off-by: Octavian Purdila <opurdila@ixiacom.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/core/sock.c | 47 +++++++++++++++++++++++++++++++++++------------
 1 file changed, 35 insertions(+), 12 deletions(-)

(limited to 'net/core/sock.c')

diff --git a/net/core/sock.c b/net/core/sock.c
index fb6080111461..e5af8d5d5b50 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1009,6 +1009,36 @@ static void sock_copy(struct sock *nsk, const struct sock *osk)
 #endif
 }
 
+/*
+ * caches using SLAB_DESTROY_BY_RCU should let .next pointer from nulls nodes
+ * un-modified. Special care is taken when initializing object to zero.
+ */
+static inline void sk_prot_clear_nulls(struct sock *sk, int size)
+{
+	if (offsetof(struct sock, sk_node.next) != 0)
+		memset(sk, 0, offsetof(struct sock, sk_node.next));
+	memset(&sk->sk_node.pprev, 0,
+	       size - offsetof(struct sock, sk_node.pprev));
+}
+
+void sk_prot_clear_portaddr_nulls(struct sock *sk, int size)
+{
+	unsigned long nulls1, nulls2;
+
+	nulls1 = offsetof(struct sock, __sk_common.skc_node.next);
+	nulls2 = offsetof(struct sock, __sk_common.skc_portaddr_node.next);
+	if (nulls1 > nulls2)
+		swap(nulls1, nulls2);
+
+	if (nulls1 != 0)
+		memset((char *)sk, 0, nulls1);
+	memset((char *)sk + nulls1 + sizeof(void *), 0,
+	       nulls2 - nulls1 - sizeof(void *));
+	memset((char *)sk + nulls2 + sizeof(void *), 0,
+	       size - nulls2 - sizeof(void *));
+}
+EXPORT_SYMBOL(sk_prot_clear_portaddr_nulls);
+
 static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
 		int family)
 {
@@ -1021,19 +1051,12 @@ static struct sock *sk_prot_alloc(struct proto *prot, gfp_t priority,
 		if (!sk)
 			return sk;
 		if (priority & __GFP_ZERO) {
-			/*
-			 * caches using SLAB_DESTROY_BY_RCU should let
-			 * sk_node.next un-modified. Special care is taken
-			 * when initializing object to zero.
-			 */
-			if (offsetof(struct sock, sk_node.next) != 0)
-				memset(sk, 0, offsetof(struct sock, sk_node.next));
-			memset(&sk->sk_node.pprev, 0,
-			       prot->obj_size - offsetof(struct sock,
-							 sk_node.pprev));
+			if (prot->clear_sk)
+				prot->clear_sk(sk, prot->obj_size);
+			else
+				sk_prot_clear_nulls(sk, prot->obj_size);
 		}
-	}
-	else
+	} else
 		sk = kmalloc(prot->obj_size, priority);
 
 	if (sk != NULL) {
-- 
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