From fbd019737d71e405f86549fd738f81e2ff3dd073 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Mon, 29 Apr 2019 14:16:19 +0800 Subject: 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: [] dump_stack+0x19/0x1b [] __schedule_bug+0x64/0x72 [] __schedule+0x9ba/0xa00 [] __cond_resched+0x26/0x30 [] _cond_resched+0x3a/0x50 [] kmem_cache_alloc_node+0x38/0x200 [] __alloc_skb+0x5d/0x2d0 [] sctp_packet_transmit+0x610/0xa20 [sctp] [] sctp_outq_flush+0x2ce/0xc00 [sctp] [] sctp_outq_uncork+0x1c/0x20 [sctp] [] sctp_cmd_interpreter.isra.22+0xc8/0x1460 [sctp] [] sctp_do_sm+0xe1/0x350 [sctp] [] sctp_primitive_ASCONF+0x3d/0x50 [sctp] [] sctp_cmd_interpreter.isra.22+0x114/0x1460 [sctp] [] sctp_do_sm+0xe1/0x350 [sctp] [] sctp_assoc_bh_rcv+0xf4/0x1b0 [sctp] [] sctp_inq_push+0x51/0x70 [sctp] [] 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 Signed-off-by: Xin Long Acked-by: Neil Horman Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/sctp/sm_statefuns.c | 35 +++++++++++++++++++++++++++-------- 1 file changed, 27 insertions(+), 8 deletions(-) (limited to 'net/sctp/sm_statefuns.c') diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c index c9ae3404b1bb..713a669d2058 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)); -- cgit v1.2.3-59-g8ed1b