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 c0786693404c ("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>
diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index c9ae340..713a669 100644
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -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));