Re: [PATCH net] sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit
From: Marcelo Ricardo Leitner
Date: Tue, 20 Nov 2018 22:56:07 -0200
> On Mon, Nov 19, 2018 at 12:39:55PM -0800, David Miller wrote:
>> From: Xin Long
>> Date: Sun, 18 Nov 2018 15:07:38 +0800
>>
>> > 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 cd305c74b0f8 ("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: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
>> > Reported-by: Xiumei Mu
>> > Signed-off-by: Xin Long
>>
>> Applied and queued up for -stable.
>
> Dave, is there a way that we can check to which versions you queued it
> up?
I queued up the patch is, and then do backports as needed.
If you think it's too complex to backport this, I'll toss it from the
-stable queue and that's what I have just done.
Re: [PATCH net] sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit
On Mon, Nov 19, 2018 at 12:39:55PM -0800, David Miller wrote:
> From: Xin Long
> Date: Sun, 18 Nov 2018 15:07:38 +0800
>
> > 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 cd305c74b0f8 ("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: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
> > Reported-by: Xiumei Mu
> > Signed-off-by: Xin Long
>
> Applied and queued up for -stable.
Dave, is there a way that we can check to which versions you queued it
up?
Asking because even though this patch fixes cac2661c53f3 (v4.10) and
the patch probably applies cleanly, it has a dependency on
cd305c74b0f8 (v4.19) and fixing the issue in older kernels either need
a different fix or backport of cd305c74b0f8 too.
Re: [PATCH net] sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit
From: Xin Long
Date: Sun, 18 Nov 2018 15:07:38 +0800
> 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 cd305c74b0f8 ("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: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
> Reported-by: Xiumei Mu
> Signed-off-by: Xin Long
Applied and queued up for -stable.
[PATCH net] sctp: count sk_wmem_alloc by skb truesize in sctp_packet_transmit
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 cd305c74b0f8 ("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: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Reported-by: Xiumei Mu
Signed-off-by: Xin Long
---
net/sctp/output.c | 21 +
1 file changed, 1 insertion(+), 20 deletions(-)
diff --git a/net/sctp/output.c b/net/sctp/output.c
index 67939ad..88dfa6a 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -396,25 +396,6 @@ enum sctp_xmit sctp_packet_append_chunk(struct sctp_packet
*packet,
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_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));
--
2.1.0
