Messages in this thread | | | Date | Thu, 1 Sep 2022 14:45:36 +0200 | Subject | Re: [PATCH net v4] net/smc: Fix possible access to freed memory in link clear | From | Wenjia Zhang <> |
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On 01.09.22 14:26, liuyacan@corp.netease.com wrote: >>> From: Yacan Liu <liuyacan@corp.netease.com> >>> >>> After modifying the QP to the Error state, all RX WR would be completed >>> with WC in IB_WC_WR_FLUSH_ERR status. Current implementation does not >>> wait for it is done, but destroy the QP and free the link group directly. >>> So there is a risk that accessing the freed memory in tasklet context. >>> >>> Here is a crash example: >>> >>> BUG: unable to handle page fault for address: ffffffff8f220860 >>> #PF: supervisor write access in kernel mode >>> #PF: error_code(0x0002) - not-present page >>> PGD f7300e067 P4D f7300e067 PUD f7300f063 PMD 8c4e45063 PTE 800ffff08c9df060 >>> Oops: 0002 [#1] SMP PTI >>> CPU: 1 PID: 0 Comm: swapper/1 Kdump: loaded Tainted: G S OE 5.10.0-0607+ #23 >>> Hardware name: Inspur NF5280M4/YZMB-00689-101, BIOS 4.1.20 07/09/2018 >>> RIP: 0010:native_queued_spin_lock_slowpath+0x176/0x1b0 >>> Code: f3 90 48 8b 32 48 85 f6 74 f6 eb d5 c1 ee 12 83 e0 03 83 ee 01 48 c1 e0 05 48 63 f6 48 05 00 c8 02 00 48 03 04 f5 00 09 98 8e <48> 89 10 8b 42 08 85 c0 75 09 f3 90 8b 42 08 85 c0 74 f7 48 8b 32 >>> RSP: 0018:ffffb3b6c001ebd8 EFLAGS: 00010086 >>> RAX: ffffffff8f220860 RBX: 0000000000000246 RCX: 0000000000080000 >>> RDX: ffff91db1f86c800 RSI: 000000000000173c RDI: ffff91db62bace00 >>> RBP: ffff91db62bacc00 R08: 0000000000000000 R09: c00000010000028b >>> R10: 0000000000055198 R11: ffffb3b6c001ea58 R12: ffff91db80e05010 >>> R13: 000000000000000a R14: 0000000000000006 R15: 0000000000000040 >>> FS: 0000000000000000(0000) GS:ffff91db1f840000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: ffffffff8f220860 CR3: 00000001f9580004 CR4: 00000000003706e0 >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> Call Trace: >>> <IRQ> >>> _raw_spin_lock_irqsave+0x30/0x40 >>> mlx5_ib_poll_cq+0x4c/0xc50 [mlx5_ib] >>> smc_wr_rx_tasklet_fn+0x56/0xa0 [smc] >>> tasklet_action_common.isra.21+0x66/0x100 >>> __do_softirq+0xd5/0x29c >>> asm_call_irq_on_stack+0x12/0x20 >>> </IRQ> >>> do_softirq_own_stack+0x37/0x40 >>> irq_exit_rcu+0x9d/0xa0 >>> sysvec_call_function_single+0x34/0x80 >>> asm_sysvec_call_function_single+0x12/0x20 >>> >>> Fixes: bd4ad57718cc ("smc: initialize IB transport incl. PD, MR, QP, CQ, event, WR") >>> Signed-off-by: Yacan Liu <liuyacan@corp.netease.com> >>> >>> --- >>> Chagen in v4: >>> -- Remove the rx_drain flag because smc_wr_rx_post() may not have been called. >>> -- Remove timeout. >>> Change in v3: >>> -- Tune commit message (Signed-Off tag, Fixes tag). >>> Tune code to avoid column length exceeding. >>> Change in v2: >>> -- Fix some compile warnings and errors. >>> --- >>> net/smc/smc_core.c | 2 ++ >>> net/smc/smc_core.h | 2 ++ >>> net/smc/smc_wr.c | 9 +++++++++ >>> net/smc/smc_wr.h | 1 + >>> 4 files changed, 14 insertions(+) >>> >>> diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c >>> index ff49a11f5..f92a916e9 100644 >>> --- a/net/smc/smc_core.c >>> +++ b/net/smc/smc_core.c >>> @@ -757,6 +757,7 @@ int smcr_link_init(struct smc_link_group *lgr, struct smc_link *lnk, >>> lnk->lgr = lgr; >>> smc_lgr_hold(lgr); /* lgr_put in smcr_link_clear() */ >>> lnk->link_idx = link_idx; >>> + lnk->wr_rx_id_compl = 0; >>> smc_ibdev_cnt_inc(lnk); >>> smcr_copy_dev_info_to_link(lnk); >>> atomic_set(&lnk->conn_cnt, 0); >>> @@ -1269,6 +1270,7 @@ void smcr_link_clear(struct smc_link *lnk, bool log) >>> smcr_buf_unmap_lgr(lnk); >>> smcr_rtoken_clear_link(lnk); >>> smc_ib_modify_qp_error(lnk); >>> + smc_wr_drain_cq(lnk); >>> smc_wr_free_link(lnk); >>> smc_ib_destroy_queue_pair(lnk); >>> smc_ib_dealloc_protection_domain(lnk); >>> diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h >>> index fe8b524ad..285f9bd8e 100644 >>> --- a/net/smc/smc_core.h >>> +++ b/net/smc/smc_core.h >>> @@ -115,8 +115,10 @@ struct smc_link { >>> dma_addr_t wr_rx_dma_addr; /* DMA address of wr_rx_bufs */ >>> dma_addr_t wr_rx_v2_dma_addr; /* DMA address of v2 rx buf*/ >>> u64 wr_rx_id; /* seq # of last recv WR */ >>> + u64 wr_rx_id_compl; /* seq # of last completed WR */ >>> u32 wr_rx_cnt; /* number of WR recv buffers */ >>> unsigned long wr_rx_tstamp; /* jiffies when last buf rx */ >>> + wait_queue_head_t wr_rx_empty_wait; /* wait for RQ empty */ >>> >>> struct ib_reg_wr wr_reg; /* WR register memory region */ >>> wait_queue_head_t wr_reg_wait; /* wait for wr_reg result */ >>> diff --git a/net/smc/smc_wr.c b/net/smc/smc_wr.c >>> index 26f8f240d..bc8793803 100644 >>> --- a/net/smc/smc_wr.c >>> +++ b/net/smc/smc_wr.c >>> @@ -454,6 +454,7 @@ static inline void smc_wr_rx_process_cqes(struct ib_wc wc[], int num) >>> >>> for (i = 0; i < num; i++) { >>> link = wc[i].qp->qp_context; >>> + link->wr_rx_id_compl = wc[i].wr_id; >>> if (wc[i].status == IB_WC_SUCCESS) { >>> link->wr_rx_tstamp = jiffies; >>> smc_wr_rx_demultiplex(&wc[i]); >>> @@ -465,6 +466,8 @@ static inline void smc_wr_rx_process_cqes(struct ib_wc wc[], int num) >>> case IB_WC_RNR_RETRY_EXC_ERR: >>> case IB_WC_WR_FLUSH_ERR: >>> smcr_link_down_cond_sched(link); >>> + if (link->wr_rx_id_compl == link->wr_rx_id) >>> + wake_up(&link->wr_rx_empty_wait); >>> break; >>> default: >>> smc_wr_rx_post(link); /* refill WR RX */ >>> @@ -631,6 +634,11 @@ static void smc_wr_init_sge(struct smc_link *lnk) >>> lnk->wr_reg.access = IB_ACCESS_LOCAL_WRITE | IB_ACCESS_REMOTE_WRITE; >>> } >>> >>> +void smc_wr_drain_cq(struct smc_link *lnk) >>> +{ >>> + wait_event(lnk->wr_rx_empty_wait, lnk->wr_rx_id_compl == lnk->wr_rx_id); >>> +} >>> + >>> void smc_wr_free_link(struct smc_link *lnk) >>> { >>> struct ib_device *ibdev; >>> @@ -889,6 +897,7 @@ int smc_wr_create_link(struct smc_link *lnk) >>> atomic_set(&lnk->wr_tx_refcnt, 0); >>> init_waitqueue_head(&lnk->wr_reg_wait); >>> atomic_set(&lnk->wr_reg_refcnt, 0); >>> + init_waitqueue_head(&lnk->wr_rx_empty_wait); >>> return rc; >>> >>> dma_unmap: >>> diff --git a/net/smc/smc_wr.h b/net/smc/smc_wr.h >>> index a54e90a11..5ca5086ae 100644 >>> --- a/net/smc/smc_wr.h >>> +++ b/net/smc/smc_wr.h >>> @@ -101,6 +101,7 @@ static inline int smc_wr_rx_post(struct smc_link *link) >>> int smc_wr_create_link(struct smc_link *lnk); >>> int smc_wr_alloc_link_mem(struct smc_link *lnk); >>> int smc_wr_alloc_lgr_mem(struct smc_link_group *lgr); >>> +void smc_wr_drain_cq(struct smc_link *lnk); >>> void smc_wr_free_link(struct smc_link *lnk); >>> void smc_wr_free_link_mem(struct smc_link *lnk); >>> void smc_wr_free_lgr_mem(struct smc_link_group *lgr); >> >> Thank you @Yacan for the effort to improve our code! And Thank you @Tony >> for such valuable suggestions and testing! >> I like the modification of this version. However, this is not a fix >> patch to upstream, since the patches "[PATCH net-next v2 00/10] optimize >> the parallelism of SMC-R connections" are still not applied. My >> sugguestions: >> - Please talk to the author (D. Wythe <alibuda@linux.alibaba.com>) of >> those patches I mentioned above, and ask if he can take your patch as a >> part of the patch serie >> - Fix patches should go to net-next >> - Please send always send your new version separately, rather than as >> reply to your previous version. That makes people confused. > > @Wenjia, Thanks a lot for your suggestions and guidance ! > > @D. Wythe, Can you include this patch in your series of patches if it is > convenient? > > Regards, > Yacan > One point I was confused, fixes should goto net, sorry!
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