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sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit

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Now sctp increases sk_wmem_alloc by 1 when doing set_owner_w for the
skb allocked in sctp_packet_transmit and decreases by 1 when freeing
this skb.

But when this skb goes through networking stack, some subcomponents
might change skb->truesize and add the same amount on sk_wmem_alloc.
However sctp doesn't know the amount to decrease by, it would cause
a leak on sk->sk_wmem_alloc and the sock can never be freed.

Xiumei found this issue when it hit esp_output_head() by using sctp
over ipsec, where skb->truesize is added and so is sk->sk_wmem_alloc.

Since sctp has used sk_wmem_queued to count for writable space since
Commit cd305c74b0 ("sctp: use sk_wmem_queued to check for writable
space"), it's ok to fix it by counting sk_wmem_alloc by skb truesize
in sctp_packet_transmit.

Fixes: cac2661c53 ("esp4: Avoid skb_cow_data whenever possible")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2018-11-18 15:07:38 +08:00 committed by David S. Miller
parent a36b5444b1
commit 02968ccf01
1 changed files with 1 additions and 20 deletions
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21
net/sctp/output.c
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@ -396,25 +396,6 @@ finish:
return retval;
}
static void sctp_packet_release_owner(struct sk_buff *skb)
{
sk_free(skb->sk);
}
static void sctp_packet_set_owner_w(struct sk_buff *skb, struct sock *sk)
{
skb_orphan(skb);
skb->sk = sk;
skb->destructor = sctp_packet_release_owner;
/*
* The data chunks have already been accounted for in sctp_sendmsg(),
* therefore only reserve a single byte to keep socket around until
* the packet has been transmitted.
*/
refcount_inc(&sk->sk_wmem_alloc);
}
static void sctp_packet_gso_append(struct sk_buff *head, struct sk_buff *skb)
{
if (SCTP_OUTPUT_CB(head)->last == head)
@ -601,7 +582,7 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t gfp)
if (!head)
goto out;
skb_reserve(head, packet->overhead + MAX_HEADER);
sctp_packet_set_owner_w(head, sk);
skb_set_owner_w(head, sk);
/* set sctp header */
sh = skb_push(head, sizeof(struct sctphdr));