sctp: handle error of sctp_sf_heartbeat() in sctp_sf_do_asconf()

[PATCH] sctp: handle error of sctp_sf_heartbeat() in sctp_sf_do_asconf()

Posted by Wentao Liang 9 months, 1 week ago

In sctp_sf_do_asconf(), SCTP_DISPOSITION_NOMEM error code returned
from sctp_sf_heartbeat() represent a failure of sent HEARTBEAT. The
return value of sctp_sf_heartbeat() needs to be checked and propagates
to caller function.

Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
---
 net/sctp/sm_statefuns.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index a0524ba8d787..89100546670a 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -3973,8 +3973,10 @@ enum sctp_disposition sctp_sf_do_asconf(struct net *net,
 	asconf_ack->dest = chunk->source;
 	sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
 	if (asoc->new_transport) {
-		sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands);
-		((struct sctp_association *)asoc)->new_transport = NULL;
+		if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands)) {
+			((struct sctp_association *)asoc)->new_transport = NULL;
+			return SCTP_DISPOSITION_NOMEM;
+		}
 	}
 
 	return SCTP_DISPOSITION_CONSUME;
-- 
2.42.0.windows.2

Re: [PATCH] sctp: handle error of sctp_sf_heartbeat() in sctp_sf_do_asconf()

Posted by Xin Long 9 months, 1 week ago

On Tue, Mar 11, 2025 at 11:22 PM Wentao Liang <vulab@iscas.ac.cn> wrote:
>
> In sctp_sf_do_asconf(), SCTP_DISPOSITION_NOMEM error code returned
> from sctp_sf_heartbeat() represent a failure of sent HEARTBEAT. The
> return value of sctp_sf_heartbeat() needs to be checked and propagates
> to caller function.

Returning this error to the caller will only result in the packet
being discarded, without reverting any changes already made in
sctp_sf_do_asconf().

Moreover, this error is not fatal. Instead, it serves as an
optimization to confirm the new destination as quickly as possible,
as introduced in:

commit 6af29ccc223b0feb6fc6112281c3fa3cdb1afddf
Author: Michio Honda <micchie@sfc.wide.ad.jp>
Date:   Thu Jun 16 17:14:34 2011 +0900

    sctp: Bundle HEAERTBEAT into ASCONF_ACK

Ignoring this error is entirely reasonable, especially considering
that running out of memory (nomem) is an unlikely scenario.

Thanks.

>
> Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
> ---
>  net/sctp/sm_statefuns.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
> index a0524ba8d787..89100546670a 100644
> --- a/net/sctp/sm_statefuns.c
> +++ b/net/sctp/sm_statefuns.c
> @@ -3973,8 +3973,10 @@ enum sctp_disposition sctp_sf_do_asconf(struct net *net,
>         asconf_ack->dest = chunk->source;
>         sctp_add_cmd_sf(commands, SCTP_CMD_REPLY, SCTP_CHUNK(asconf_ack));
>         if (asoc->new_transport) {
> -               sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands);
> -               ((struct sctp_association *)asoc)->new_transport = NULL;
> +               if (SCTP_DISPOSITION_NOMEM == sctp_sf_heartbeat(ep, asoc, type, asoc->new_transport, commands)) {
> +                       ((struct sctp_association *)asoc)->new_transport = NULL;
> +                       return SCTP_DISPOSITION_NOMEM;
> +               }
>         }
>
>         return SCTP_DISPOSITION_CONSUME;
> --
> 2.42.0.windows.2
>

Re: [PATCH] sctp: handle error of sctp_sf_heartbeat() in sctp_sf_do_asconf()

Posted by Markus Elfring 9 months, 1 week ago

> In sctp_sf_do_asconf(), SCTP_DISPOSITION_NOMEM error code returned
> from sctp_sf_heartbeat() represent a failure of sent HEARTBEAT. The

                                                       heartbeat?

Would the error predicate “return value != SCTP_DISPOSITION_CONSUME” be safer?
https://elixir.bootlin.com/linux/v6.14-rc6/source/include/net/sctp/sm.h#L43


> return value of sctp_sf_heartbeat() needs to be checked and propagates
> to caller function.

Will imperative wordings be more desirable for such a change description?
https://web.git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?h=v6.14-rc6#n94

Regards,
Markus