From 458be024ef5f72f1697d5d55289c4ed45f8ee910 Mon Sep 17 00:00:00 2001 From: Parthasarathy Bhuvaragan Date: Tue, 22 Aug 2017 12:28:40 +0200 Subject: [PATCH] tipc: remove subscription references only for pending timers In commit, 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list"), we delete the subscription from the subscribers list and from nametable unconditionally. This leads to the following bug if the timer running tipc_subscrp_timeout() in another CPU accesses the subscription list after the subscription delete request. [39.570] general protection fault: 0000 [#1] SMP :: [39.574] task: ffffffff81c10540 task.stack: ffffffff81c00000 [39.575] RIP: 0010:tipc_subscrp_timeout+0x32/0x80 [tipc] [39.576] RSP: 0018:ffff88003ba03e90 EFLAGS: 00010282 [39.576] RAX: dead000000000200 RBX: ffff88003f0f3600 RCX: 0000000000000101 [39.577] RDX: dead000000000100 RSI: 0000000000000201 RDI: ffff88003f0d7948 [39.578] RBP: ffff88003ba03ea0 R08: 0000000000000001 R09: ffff88003ba03ef8 [39.579] R10: 000000000000014f R11: 0000000000000000 R12: ffff88003f0d7948 [39.580] R13: ffff88003f0f3618 R14: ffffffffa006c250 R15: ffff88003f0f3600 [39.581] FS: 0000000000000000(0000) GS:ffff88003ba00000(0000) knlGS:0000000000000000 [39.582] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [39.583] CR2: 00007f831c6e0714 CR3: 000000003d3b0000 CR4: 00000000000006f0 [39.584] Call Trace: [39.584] [39.585] call_timer_fn+0x3d/0x180 [39.585] ? tipc_subscrb_rcv_cb+0x260/0x260 [tipc] [39.586] run_timer_softirq+0x168/0x1f0 [39.586] ? sched_clock_cpu+0x16/0xc0 [39.587] __do_softirq+0x9b/0x2de [39.587] irq_exit+0x60/0x70 [39.588] smp_apic_timer_interrupt+0x3d/0x50 [39.588] apic_timer_interrupt+0x86/0x90 [39.589] RIP: 0010:default_idle+0x20/0xf0 [39.589] RSP: 0018:ffffffff81c03e58 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff10 [39.590] RAX: 0000000000000000 RBX: ffffffff81c10540 RCX: 0000000000000000 [39.591] RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 [39.592] RBP: ffffffff81c03e68 R08: 0000000000000000 R09: 0000000000000000 [39.593] R10: ffffc90001cbbe00 R11: 0000000000000000 R12: 0000000000000000 [39.594] R13: ffffffff81c10540 R14: 0000000000000000 R15: 0000000000000000 [39.595] :: [39.603] RIP: tipc_subscrp_timeout+0x32/0x80 [tipc] RSP: ffff88003ba03e90 [39.604] ---[ end trace 79ce94b7216cb459 ]--- Fixes: 139bb36f754a ("tipc: advance the time of deleting subscription from subscriber->subscrp_list") Signed-off-by: Parthasarathy Bhuvaragan Signed-off-by: David S. Miller --- net/tipc/subscr.c | 19 +++++++------------ 1 file changed, 7 insertions(+), 12 deletions(-) diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c index 0bf91cd3733c..f2c81f42dfda 100644 --- a/net/tipc/subscr.c +++ b/net/tipc/subscr.c @@ -52,7 +52,6 @@ struct tipc_subscriber { struct list_head subscrp_list; }; -static void tipc_subscrp_delete(struct tipc_subscription *sub); static void tipc_subscrb_put(struct tipc_subscriber *subscriber); /** @@ -197,15 +196,19 @@ static void tipc_subscrb_subscrp_delete(struct tipc_subscriber *subscriber, { struct list_head *subscription_list = &subscriber->subscrp_list; struct tipc_subscription *sub, *temp; + u32 timeout; spin_lock_bh(&subscriber->lock); list_for_each_entry_safe(sub, temp, subscription_list, subscrp_list) { if (s && memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) continue; - tipc_nametbl_unsubscribe(sub); - list_del(&sub->subscrp_list); - tipc_subscrp_delete(sub); + timeout = htohl(sub->evt.s.timeout, sub->swap); + if (timeout == TIPC_WAIT_FOREVER || del_timer(&sub->timer)) { + tipc_nametbl_unsubscribe(sub); + list_del(&sub->subscrp_list); + tipc_subscrp_put(sub); + } if (s) break; @@ -236,14 +239,6 @@ static void tipc_subscrb_delete(struct tipc_subscriber *subscriber) tipc_subscrb_put(subscriber); } -static void tipc_subscrp_delete(struct tipc_subscription *sub) -{ - u32 timeout = htohl(sub->evt.s.timeout, sub->swap); - - if (timeout == TIPC_WAIT_FOREVER || del_timer(&sub->timer)) - tipc_subscrp_put(sub); -} - static void tipc_subscrp_cancel(struct tipc_subscr *s, struct tipc_subscriber *subscriber) {