* [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
@ 2013-08-09 13:27 ` Daniel Borkmann
0 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2013-08-09 13:27 UTC (permalink / raw)
To: davem; +Cc: netdev, linux-sctp
Probably this one is quite unlikely to be triggered, but it's more safe
to hold a pointer to asoc (instead of dereferencing), free the packet
chunks first, and access asoc though the pointer after we have called
sctp_transport_destroy_rcu() where the transport is being kfree()'d.
Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
for deferred call_rcu's"). I also did the 8c98653f regression test and
it's fine that way.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
---
v1->v2: do sctp_packet_free before call_rcu
net/sctp/transport.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index bdbbc3f..c691455 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
*/
static void sctp_transport_destroy(struct sctp_transport *transport)
{
+ struct sctp_association *asoc = transport->asoc;
+
if (unlikely(!transport->dead)) {
WARN(1, "Attempt to destroy undead transport %p!\n", transport);
return;
}
- call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
-
sctp_packet_free(&transport->packet);
- if (transport->asoc)
- sctp_association_put(transport->asoc);
+ call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
+
+ if (asoc != NULL)
+ sctp_association_put(asoc);
}
/* Start T3_rtx timer if it is not already running and update the heartbeat
--
1.7.11.7
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
@ 2013-08-09 13:27 ` Daniel Borkmann
0 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2013-08-09 13:27 UTC (permalink / raw)
To: davem; +Cc: netdev, linux-sctp
Probably this one is quite unlikely to be triggered, but it's more safe
to hold a pointer to asoc (instead of dereferencing), free the packet
chunks first, and access asoc though the pointer after we have called
sctp_transport_destroy_rcu() where the transport is being kfree()'d.
Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
for deferred call_rcu's"). I also did the 8c98653f regression test and
it's fine that way.
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
---
v1->v2: do sctp_packet_free before call_rcu
net/sctp/transport.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/net/sctp/transport.c b/net/sctp/transport.c
index bdbbc3f..c691455 100644
--- a/net/sctp/transport.c
+++ b/net/sctp/transport.c
@@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
*/
static void sctp_transport_destroy(struct sctp_transport *transport)
{
+ struct sctp_association *asoc = transport->asoc;
+
if (unlikely(!transport->dead)) {
WARN(1, "Attempt to destroy undead transport %p!\n", transport);
return;
}
- call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
-
sctp_packet_free(&transport->packet);
- if (transport->asoc)
- sctp_association_put(transport->asoc);
+ call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
+
+ if (asoc != NULL)
+ sctp_association_put(asoc);
}
/* Start T3_rtx timer if it is not already running and update the heartbeat
--
1.7.11.7
^ permalink raw reply related [flat|nested] 6+ messages in thread* Re: [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
2013-08-09 13:27 ` Daniel Borkmann
@ 2013-08-09 13:57 ` Vlad Yasevich
-1 siblings, 0 replies; 6+ messages in thread
From: Vlad Yasevich @ 2013-08-09 13:57 UTC (permalink / raw)
To: Daniel Borkmann; +Cc: davem, netdev, linux-sctp
On 08/09/2013 09:27 AM, Daniel Borkmann wrote:
> Probably this one is quite unlikely to be triggered, but it's more safe
> to hold a pointer to asoc (instead of dereferencing), free the packet
> chunks first, and access asoc though the pointer after we have called
> sctp_transport_destroy_rcu() where the transport is being kfree()'d.
> Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
> for deferred call_rcu's"). I also did the 8c98653f regression test and
> it's fine that way.
>
> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
> ---
> v1->v2: do sctp_packet_free before call_rcu
>
> net/sctp/transport.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/net/sctp/transport.c b/net/sctp/transport.c
> index bdbbc3f..c691455 100644
> --- a/net/sctp/transport.c
> +++ b/net/sctp/transport.c
> @@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
> */
> static void sctp_transport_destroy(struct sctp_transport *transport)
> {
> + struct sctp_association *asoc = transport->asoc;
> +
> if (unlikely(!transport->dead)) {
> WARN(1, "Attempt to destroy undead transport %p!\n", transport);
> return;
> }
>
> - call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
> -
> sctp_packet_free(&transport->packet);
>
> - if (transport->asoc)
> - sctp_association_put(transport->asoc);
> + call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
> +
> + if (asoc != NULL)
> + sctp_association_put(asoc);
I think it is safe to move call_rcu to be the last call in this
function. This should never be a last ref on the association. If
by some chance it is, we'll get the same warning.
And if you move call_rcu(), this becomes an ever smaller patch :)
-vlad
> }
>
> /* Start T3_rtx timer if it is not already running and update the heartbeat
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
@ 2013-08-09 13:57 ` Vlad Yasevich
0 siblings, 0 replies; 6+ messages in thread
From: Vlad Yasevich @ 2013-08-09 13:57 UTC (permalink / raw)
To: Daniel Borkmann; +Cc: davem, netdev, linux-sctp
On 08/09/2013 09:27 AM, Daniel Borkmann wrote:
> Probably this one is quite unlikely to be triggered, but it's more safe
> to hold a pointer to asoc (instead of dereferencing), free the packet
> chunks first, and access asoc though the pointer after we have called
> sctp_transport_destroy_rcu() where the transport is being kfree()'d.
> Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
> for deferred call_rcu's"). I also did the 8c98653f regression test and
> it's fine that way.
>
> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
> ---
> v1->v2: do sctp_packet_free before call_rcu
>
> net/sctp/transport.c | 10 ++++++----
> 1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/net/sctp/transport.c b/net/sctp/transport.c
> index bdbbc3f..c691455 100644
> --- a/net/sctp/transport.c
> +++ b/net/sctp/transport.c
> @@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
> */
> static void sctp_transport_destroy(struct sctp_transport *transport)
> {
> + struct sctp_association *asoc = transport->asoc;
> +
> if (unlikely(!transport->dead)) {
> WARN(1, "Attempt to destroy undead transport %p!\n", transport);
> return;
> }
>
> - call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
> -
> sctp_packet_free(&transport->packet);
>
> - if (transport->asoc)
> - sctp_association_put(transport->asoc);
> + call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
> +
> + if (asoc != NULL)
> + sctp_association_put(asoc);
I think it is safe to move call_rcu to be the last call in this
function. This should never be a last ref on the association. If
by some chance it is, we'll get the same warning.
And if you move call_rcu(), this becomes an ever smaller patch :)
-vlad
> }
>
> /* Start T3_rtx timer if it is not already running and update the heartbeat
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
2013-08-09 13:57 ` Vlad Yasevich
@ 2013-08-09 13:59 ` Daniel Borkmann
-1 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2013-08-09 13:59 UTC (permalink / raw)
To: Vlad Yasevich; +Cc: davem, netdev, linux-sctp
On 08/09/2013 03:57 PM, Vlad Yasevich wrote:
> On 08/09/2013 09:27 AM, Daniel Borkmann wrote:
>> Probably this one is quite unlikely to be triggered, but it's more safe
>> to hold a pointer to asoc (instead of dereferencing), free the packet
>> chunks first, and access asoc though the pointer after we have called
>> sctp_transport_destroy_rcu() where the transport is being kfree()'d.
>> Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
>> for deferred call_rcu's"). I also did the 8c98653f regression test and
>> it's fine that way.
>>
>> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
>> ---
>> v1->v2: do sctp_packet_free before call_rcu
>>
>> net/sctp/transport.c | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/sctp/transport.c b/net/sctp/transport.c
>> index bdbbc3f..c691455 100644
>> --- a/net/sctp/transport.c
>> +++ b/net/sctp/transport.c
>> @@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
>> */
>> static void sctp_transport_destroy(struct sctp_transport *transport)
>> {
>> + struct sctp_association *asoc = transport->asoc;
>> +
>> if (unlikely(!transport->dead)) {
>> WARN(1, "Attempt to destroy undead transport %p!\n", transport);
>> return;
>> }
>>
>> - call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
>> -
>> sctp_packet_free(&transport->packet);
>>
>> - if (transport->asoc)
>> - sctp_association_put(transport->asoc);
>> + call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
>> +
>> + if (asoc != NULL)
>> + sctp_association_put(asoc);
>
> I think it is safe to move call_rcu to be the last call in this function. This should never be a last ref on the association. If
> by some chance it is, we'll get the same warning.
>
> And if you move call_rcu(), this becomes an ever smaller patch :)
Ok, that's also a way to go. Will send v3. :-)
> -vlad
>> }
>>
>> /* Start T3_rtx timer if it is not already running and update the heartbeat
>>
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption
@ 2013-08-09 13:59 ` Daniel Borkmann
0 siblings, 0 replies; 6+ messages in thread
From: Daniel Borkmann @ 2013-08-09 13:59 UTC (permalink / raw)
To: Vlad Yasevich; +Cc: davem, netdev, linux-sctp
On 08/09/2013 03:57 PM, Vlad Yasevich wrote:
> On 08/09/2013 09:27 AM, Daniel Borkmann wrote:
>> Probably this one is quite unlikely to be triggered, but it's more safe
>> to hold a pointer to asoc (instead of dereferencing), free the packet
>> chunks first, and access asoc though the pointer after we have called
>> sctp_transport_destroy_rcu() where the transport is being kfree()'d.
>> Introduced by commit 8c98653f ("sctp: sctp_close: fix release of bindings
>> for deferred call_rcu's"). I also did the 8c98653f regression test and
>> it's fine that way.
>>
>> Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
>> ---
>> v1->v2: do sctp_packet_free before call_rcu
>>
>> net/sctp/transport.c | 10 ++++++----
>> 1 file changed, 6 insertions(+), 4 deletions(-)
>>
>> diff --git a/net/sctp/transport.c b/net/sctp/transport.c
>> index bdbbc3f..c691455 100644
>> --- a/net/sctp/transport.c
>> +++ b/net/sctp/transport.c
>> @@ -176,17 +176,19 @@ static void sctp_transport_destroy_rcu(struct rcu_head *head)
>> */
>> static void sctp_transport_destroy(struct sctp_transport *transport)
>> {
>> + struct sctp_association *asoc = transport->asoc;
>> +
>> if (unlikely(!transport->dead)) {
>> WARN(1, "Attempt to destroy undead transport %p!\n", transport);
>> return;
>> }
>>
>> - call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
>> -
>> sctp_packet_free(&transport->packet);
>>
>> - if (transport->asoc)
>> - sctp_association_put(transport->asoc);
>> + call_rcu(&transport->rcu, sctp_transport_destroy_rcu);
>> +
>> + if (asoc != NULL)
>> + sctp_association_put(asoc);
>
> I think it is safe to move call_rcu to be the last call in this function. This should never be a last ref on the association. If
> by some chance it is, we'll get the same warning.
>
> And if you move call_rcu(), this becomes an ever smaller patch :)
Ok, that's also a way to go. Will send v3. :-)
> -vlad
>> }
>>
>> /* Start T3_rtx timer if it is not already running and update the heartbeat
>>
>
> --
> To unsubscribe from this list: send the line "unsubscribe netdev" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2013-08-09 13:59 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
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2013-08-09 13:27 [PATCH net v2] net: sctp: sctp_transport_destroy{,_rcu}: fix potential pointer corruption Daniel Borkmann
2013-08-09 13:27 ` Daniel Borkmann
2013-08-09 13:57 ` Vlad Yasevich
2013-08-09 13:57 ` Vlad Yasevich
2013-08-09 13:59 ` Daniel Borkmann
2013-08-09 13:59 ` Daniel Borkmann
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