CVE-2011-2482 (published 2013-06-08T13:05Z)

A certain Red Hat patch to the sctp_sock_migrate function in net/sctp/socket.c in the Linux kernel before 2.6.21, as used in Red Hat Enterprise Linux (RHEL) 5, allows remote attackers to cause a denial of service (NULL pointer dereference and OOPS) via a crafted SCTP packet.

Severity: HIGH
CVSS v2 base score: 7.8 (AV:N/AC:L/Au:N/C:N/I:N/A:C)
CVSS v3 base score: 7.5, HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: CWE-476
cwe_name: NULL Pointer Dereference
description: The product dereferences a pointer that it expects to be valid but is NULL.
extended_description: 
            
            
            
         
         

Fix information:
repo_url: https://github.com/torvalds/linux
commit_details: repo_url: https://github.com/torvalds/linux
author: Tsutomu Fujii
author_date: 2007-04-17 12:49:53-07:00
msg: [SCTP]: Fix assertion (!atomic_read(&sk->sk_rmem_alloc)) failed message

In current implementation, LKSCTP does receive buffer accounting for
data in sctp_receive_queue and pd_lobby. However, LKSCTP don't do
accounting for data in frag_list when data is fragmented. In addition,
LKSCTP doesn't do accounting for data in reasm and lobby queue in
structure sctp_ulpq.
When there are date in these queue, assertion failed message is printed
in inet_sock_destruct because sk_rmem_alloc of oldsk does not become 0
when socket is destroyed.

Signed-off-by: Tsutomu Fujii <t-fujii@nb.jp.nec.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
repository: repo_url: https://github.com/torvalds/linux
repo_name: torvalds/linux
description: Linux kernel source tree
repo_language: C
owner: torvalds
file_changes: filename: socket.c
change_type: ModificationType.MODIFY
diff: @@ -5638,6 +5638,36 @@ void sctp_wait_for_close(struct sock *sk, long timeout)
 	finish_wait(sk->sk_sleep, &wait);
 }
 
+static void sctp_sock_rfree_frag(struct sk_buff *skb)
+{
+	struct sk_buff *frag;
+
+	if (!skb->data_len)
+		goto done;
+
+	/* Don't forget the fragments. */
+	for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next)
+		sctp_sock_rfree_frag(frag);
+
+done:
+	sctp_sock_rfree(skb);
+}
+
+static void sctp_skb_set_owner_r_frag(struct sk_buff *skb, struct sock *sk)
+{
+	struct sk_buff *frag;
+
+	if (!skb->data_len)
+		goto done;
+
+	/* Don't forget the fragments. */
+	for (frag = skb_shinfo(skb)->frag_list; frag; frag = frag->next)
+		sctp_skb_set_owner_r_frag(frag, sk);
+
+done:
+	sctp_skb_set_owner_r(skb, sk);
+}
+
 /* Populate the fields of the newsk from the oldsk and migrate the assoc
  * and its messages to the newsk.
  */
@@ -5692,10 +5722,10 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 	sctp_skb_for_each(skb, &oldsk->sk_receive_queue, tmp) {
 		event = sctp_skb2event(skb);
 		if (event->asoc == assoc) {
-			sctp_sock_rfree(skb);
+			sctp_sock_rfree_frag(skb);
 			__skb_unlink(skb, &oldsk->sk_receive_queue);
 			__skb_queue_tail(&newsk->sk_receive_queue, skb);
-			sctp_skb_set_owner_r(skb, newsk);
+			sctp_skb_set_owner_r_frag(skb, newsk);
 		}
 	}
 
@@ -5723,10 +5753,10 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 		sctp_skb_for_each(skb, &oldsp->pd_lobby, tmp) {
 			event = sctp_skb2event(skb);
 			if (event->asoc == assoc) {
-				sctp_sock_rfree(skb);
+				sctp_sock_rfree_frag(skb);
 				__skb_unlink(skb, &oldsp->pd_lobby);
 				__skb_queue_tail(queue, skb);
-				sctp_skb_set_owner_r(skb, newsk);
+				sctp_skb_set_owner_r_frag(skb, newsk);
 			}
 		}
 
@@ -5738,6 +5768,16 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 
 	}
 
+	sctp_skb_for_each(skb, &assoc->ulpq.reasm, tmp) {
+		sctp_sock_rfree_frag(skb);
+		sctp_skb_set_owner_r_frag(skb, newsk);
+	}
+
+	sctp_skb_for_each(skb, &assoc->ulpq.lobby, tmp) {
+		sctp_sock_rfree_frag(skb);
+		sctp_skb_set_owner_r_frag(skb, newsk);
+	}
+
 	/* Set the type of socket to indicate that it is peeled off from the
 	 * original UDP-style socket or created with the accept() call on a
 	 * TCP-style socket..

programming_language: C