From 2b33eb8f1b3e8c2f87cfdbc8cc117f6bdfabc6ec Mon Sep 17 00:00:00 2001 From: Guangguan Wang Date: Wed, 11 Dec 2024 17:21:16 +0800 Subject: [PATCH] net/smc: protect link down work from execute after lgr freed link down work may be scheduled before lgr freed but execute after lgr freed, which may result in crash. So it is need to hold a reference before shedule link down work, and put the reference after work executed or canceled. The relevant crash call stack as follows: list_del corruption. prev->next should be ffffb638c9c0fe20, but was 0000000000000000 ------------[ cut here ]------------ kernel BUG at lib/list_debug.c:51! invalid opcode: 0000 [#1] SMP NOPTI CPU: 6 PID: 978112 Comm: kworker/6:119 Kdump: loaded Tainted: G #1 Hardware name: Alibaba Cloud Alibaba Cloud ECS, BIOS 2221b89 04/01/2014 Workqueue: events smc_link_down_work [smc] RIP: 0010:__list_del_entry_valid.cold+0x31/0x47 RSP: 0018:ffffb638c9c0fdd8 EFLAGS: 00010086 RAX: 0000000000000054 RBX: ffff942fb75e5128 RCX: 0000000000000000 RDX: ffff943520930aa0 RSI: ffff94352091fc80 RDI: ffff94352091fc80 RBP: 0000000000000000 R08: 0000000000000000 R09: ffffb638c9c0fc38 R10: ffffb638c9c0fc30 R11: ffffffffa015eb28 R12: 0000000000000002 R13: ffffb638c9c0fe20 R14: 0000000000000001 R15: ffff942f9cd051c0 FS: 0000000000000000(0000) GS:ffff943520900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4f25214000 CR3: 000000025fbae004 CR4: 00000000007706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 PKRU: 55555554 Call Trace: rwsem_down_write_slowpath+0x17e/0x470 smc_link_down_work+0x3c/0x60 [smc] process_one_work+0x1ac/0x350 worker_thread+0x49/0x2f0 ? rescuer_thread+0x360/0x360 kthread+0x118/0x140 ? __kthread_bind_mask+0x60/0x60 ret_from_fork+0x1f/0x30 Fixes: 541afa10c126 ("net/smc: add smcr_port_err() and smcr_link_down() processing") Signed-off-by: Guangguan Wang Reviewed-by: Tony Lu Signed-off-by: David S. Miller --- net/smc/smc_core.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 500952c2e67bab..3b125d348b4aed 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -1818,7 +1818,9 @@ void smcr_link_down_cond_sched(struct smc_link *lnk) { if (smc_link_downing(&lnk->state)) { trace_smcr_link_down(lnk, __builtin_return_address(0)); - schedule_work(&lnk->link_down_wrk); + smcr_link_hold(lnk); /* smcr_link_put in link_down_wrk */ + if (!schedule_work(&lnk->link_down_wrk)) + smcr_link_put(lnk); } } @@ -1850,11 +1852,14 @@ static void smc_link_down_work(struct work_struct *work) struct smc_link_group *lgr = link->lgr; if (list_empty(&lgr->list)) - return; + goto out; wake_up_all(&lgr->llc_msg_waiter); down_write(&lgr->llc_conf_mutex); smcr_link_down(link); up_write(&lgr->llc_conf_mutex); + +out: + smcr_link_put(link); /* smcr_link_hold by schedulers of link_down_work */ } static int smc_vlan_by_tcpsk_walk(struct net_device *lower_dev,