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sctp: avoid running the sctp state machine recursively 

Ying triggered a call trace when doing an asconf testing:

  BUG: scheduling while atomic: swapper/12/0/0x10000100
  Call Trace:
   <IRQ>  [<ffffffffa4375904>] dump_stack+0x19/0x1b
   [<ffffffffa436fcaf>] __schedule_bug+0x64/0x72
   [<ffffffffa437b93a>] __schedule+0x9ba/0xa00
   [<ffffffffa3cd5326>] __cond_resched+0x26/0x30
   [<ffffffffa437bc4a>] _cond_resched+0x3a/0x50
   [<ffffffffa3e22be8>] kmem_cache_alloc_node+0x38/0x200
   [<ffffffffa423512d>] __alloc_skb+0x5d/0x2d0
   [<ffffffffc0995320>] sctp_packet_transmit+0x610/0xa20 [sctp]
   [<ffffffffc098510e>] sctp_outq_flush+0x2ce/0xc00 [sctp]
   [<ffffffffc098646c>] sctp_outq_uncork+0x1c/0x20 [sctp]
   [<ffffffffc0977338>] sctp_cmd_interpreter.isra.22+0xc8/0x1460 [sctp]
   [<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp]
   [<ffffffffc099443d>] sctp_primitive_ASCONF+0x3d/0x50 [sctp]
   [<ffffffffc0977384>] sctp_cmd_interpreter.isra.22+0x114/0x1460 [sctp]
   [<ffffffffc0976ad1>] sctp_do_sm+0xe1/0x350 [sctp]
   [<ffffffffc097b3a4>] sctp_assoc_bh_rcv+0xf4/0x1b0 [sctp]
   [<ffffffffc09840f1>] sctp_inq_push+0x51/0x70 [sctp]
   [<ffffffffc099732b>] sctp_rcv+0xa8b/0xbd0 [sctp]

As it shows, the first sctp_do_sm() running under atomic context (NET_RX
softirq) invoked sctp_primitive_ASCONF() that uses GFP_KERNEL flag later,
and this flag is supposed to be used in non-atomic context only. Besides,
sctp_do_sm() was called recursively, which is not expected.

Vlad tried to fix this recursive call in Commit c078669340 ("sctp: Fix
oops when sending queued ASCONF chunks") by introducing a new command
SCTP_CMD_SEND_NEXT_ASCONF. But it didn't work as this command is still
used in the first sctp_do_sm() call, and sctp_primitive_ASCONF() will
be called in this command again.

To avoid calling sctp_do_sm() recursively, we send the next queued ASCONF
not by sctp_primitive_ASCONF(), but by sctp_sf_do_prm_asconf() in the 1st
sctp_do_sm() directly.

Reported-by: Ying Xu <yinxu@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2019-04-29 14:16:19 +08:00 committed by David S. Miller
parent 37e9c087c8
commit fbd019737d
3 changed files with 27 additions and 38 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/sctp/command.h
View File

@ -105,7 +105,6 @@ enum sctp_verb {
SCTP_CMD_T1_RETRAN, /* Mark for retransmission after T1 timeout */
SCTP_CMD_UPDATE_INITTAG, /* Update peer inittag */
SCTP_CMD_SEND_MSG, /* Send the whole use message */
SCTP_CMD_SEND_NEXT_ASCONF, /* Send the next ASCONF after ACK */
SCTP_CMD_PURGE_ASCONF_QUEUE, /* Purge all asconf queues.*/
SCTP_CMD_SET_ASOC, /* Restore association context */
SCTP_CMD_LAST

29
net/sctp/sm_sideeffect.c
View File

@ -1112,32 +1112,6 @@ static void sctp_cmd_send_msg(struct sctp_association *asoc,
}
/* Sent the next ASCONF packet currently stored in the association.
* This happens after the ASCONF_ACK was succeffully processed.
*/
static void sctp_cmd_send_asconf(struct sctp_association *asoc)
{
struct net *net = sock_net(asoc->base.sk);
/* Send the next asconf chunk from the addip chunk
* queue.
*/
if (!list_empty(&asoc->addip_chunk_list)) {
struct list_head *entry = asoc->addip_chunk_list.next;
struct sctp_chunk *asconf = list_entry(entry,
struct sctp_chunk, list);
list_del_init(entry);
/* Hold the chunk until an ASCONF_ACK is received. */
sctp_chunk_hold(asconf);
if (sctp_primitive_ASCONF(net, asoc, asconf))
sctp_chunk_free(asconf);
else
asoc->addip_last_asconf = asconf;
}
}
/* These three macros allow us to pull the debugging code out of the
* main flow of sctp_do_sm() to keep attention focused on the real
* functionality there.
@ -1783,9 +1757,6 @@ static int sctp_cmd_interpreter(enum sctp_event_type event_type,
}
sctp_cmd_send_msg(asoc, cmd->obj.msg, gfp);
break;
case SCTP_CMD_SEND_NEXT_ASCONF:
sctp_cmd_send_asconf(asoc);
break;
case SCTP_CMD_PURGE_ASCONF_QUEUE:
sctp_asconf_queue_teardown(asoc);
break;

35
net/sctp/sm_statefuns.c
View File

@ -3824,6 +3824,29 @@ enum sctp_disposition sctp_sf_do_asconf(struct net *net,
return SCTP_DISPOSITION_CONSUME;
}
static enum sctp_disposition sctp_send_next_asconf(
struct net *net,
const struct sctp_endpoint *ep,
struct sctp_association *asoc,
const union sctp_subtype type,
struct sctp_cmd_seq *commands)
{
struct sctp_chunk *asconf;
struct list_head *entry;
if (list_empty(&asoc->addip_chunk_list))
return SCTP_DISPOSITION_CONSUME;
entry = asoc->addip_chunk_list.next;
asconf = list_entry(entry, struct sctp_chunk, list);
list_del_init(entry);
sctp_chunk_hold(asconf);
asoc->addip_last_asconf = asconf;
return sctp_sf_do_prm_asconf(net, ep, asoc, type, asconf, commands);
}
/*
* ADDIP Section 4.3 General rules for address manipulation
* When building TLV parameters for the ASCONF Chunk that will add or
@ -3915,14 +3938,10 @@ enum sctp_disposition sctp_sf_do_asconf_ack(struct net *net,
SCTP_TO(SCTP_EVENT_TIMEOUT_T4_RTO));
if (!sctp_process_asconf_ack((struct sctp_association *)asoc,
asconf_ack)) {
/* Successfully processed ASCONF_ACK. We can
* release the next asconf if we have one.
*/
sctp_add_cmd_sf(commands, SCTP_CMD_SEND_NEXT_ASCONF,
SCTP_NULL());
return SCTP_DISPOSITION_CONSUME;
}
asconf_ack))
return sctp_send_next_asconf(net, ep,
(struct sctp_association *)asoc,
type, commands);
abort = sctp_make_abort(asoc, asconf_ack,
sizeof(struct sctp_errhdr));