From: Xin Long lucien.xin@gmail.com
[ Upstream commit 057a10fa1f73d745c8e69aa54ab147715f5630ae ]
A call trace was found in Hangbin's Codenomicon testing with debug kernel:
[ 2615.981988] ODEBUG: free active (active state 0) object type: timer_list hint: sctp_generate_proto_unreach_event+0x0/0x3a0 [sctp] [ 2615.995050] WARNING: CPU: 17 PID: 0 at lib/debugobjects.c:328 debug_print_object+0x199/0x2b0 [ 2616.095934] RIP: 0010:debug_print_object+0x199/0x2b0 [ 2616.191533] Call Trace: [ 2616.194265] <IRQ> [ 2616.202068] debug_check_no_obj_freed+0x25e/0x3f0 [ 2616.207336] slab_free_freelist_hook+0xeb/0x140 [ 2616.220971] kfree+0xd6/0x2c0 [ 2616.224293] rcu_do_batch+0x3bd/0xc70 [ 2616.243096] rcu_core+0x8b9/0xd00 [ 2616.256065] __do_softirq+0x23d/0xacd [ 2616.260166] irq_exit+0x236/0x2a0 [ 2616.263879] smp_apic_timer_interrupt+0x18d/0x620 [ 2616.269138] apic_timer_interrupt+0xf/0x20 [ 2616.273711] </IRQ>
This is because it holds asoc when transport->proto_unreach_timer starts and puts asoc when the timer stops, and without holding transport the transport could be freed when the timer is still running.
So fix it by holding/putting transport instead for proto_unreach_timer in transport, just like other timers in transport.
v1->v2: - Also use sctp_transport_put() for the "out_unlock:" path in sctp_generate_proto_unreach_event(), as Marcelo noticed.
Fixes: 50b5d6ad6382 ("sctp: Fix a race between ICMP protocol unreachable and connect()") Reported-by: Hangbin Liu liuhangbin@gmail.com Signed-off-by: Xin Long lucien.xin@gmail.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Link: https://lore.kernel.org/r/102788809b554958b13b95d33440f5448113b8d6.160533137... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/input.c | 4 ++-- net/sctp/sm_sideeffect.c | 4 ++-- net/sctp/transport.c | 2 +- 3 files changed, 5 insertions(+), 5 deletions(-)
--- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -449,7 +449,7 @@ void sctp_icmp_proto_unreachable(struct else { if (!mod_timer(&t->proto_unreach_timer, jiffies + (HZ/20))) - sctp_association_hold(asoc); + sctp_transport_hold(t); } } else { struct net *net = sock_net(sk); @@ -458,7 +458,7 @@ void sctp_icmp_proto_unreachable(struct "encountered!\n", __func__);
if (del_timer(&t->proto_unreach_timer)) - sctp_association_put(asoc); + sctp_transport_put(t);
sctp_do_sm(net, SCTP_EVENT_T_OTHER, SCTP_ST_OTHER(SCTP_EVENT_ICMP_PROTO_UNREACH), --- a/net/sctp/sm_sideeffect.c +++ b/net/sctp/sm_sideeffect.c @@ -417,7 +417,7 @@ void sctp_generate_proto_unreach_event(u /* Try again later. */ if (!mod_timer(&transport->proto_unreach_timer, jiffies + (HZ/20))) - sctp_association_hold(asoc); + sctp_transport_hold(transport); goto out_unlock; }
@@ -433,7 +433,7 @@ void sctp_generate_proto_unreach_event(u
out_unlock: bh_unlock_sock(sk); - sctp_association_put(asoc); + sctp_transport_put(transport); }
--- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -146,7 +146,7 @@ void sctp_transport_free(struct sctp_tra
/* Delete the ICMP proto unreachable timer if it's active. */ if (del_timer(&transport->proto_unreach_timer)) - sctp_association_put(transport->asoc); + sctp_transport_put(transport);
sctp_transport_put(transport); }