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    Subject[PATCH 5.19 148/192] net/smc: Fix possible access to freed memory in link clear
    Date
    From: Yacan Liu <liuyacan@corp.netease.com>

    [ Upstream commit e9b1a4f867ae9c1dbd1d71cd09cbdb3239fb4968 ]

    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>
    Reviewed-by: Tony Lu <tonylu@linux.alibaba.com>
    Signed-off-by: David S. Miller <davem@davemloft.net>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    net/smc/smc_core.c | 1 +
    net/smc/smc_core.h | 2 ++
    net/smc/smc_wr.c | 5 +++++
    net/smc/smc_wr.h | 5 +++++
    4 files changed, 13 insertions(+)

    diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c
    index f40f6ed0fbdb4..1f3bb1f6b1f7b 100644
    --- a/net/smc/smc_core.c
    +++ b/net/smc/smc_core.c
    @@ -755,6 +755,7 @@ 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);
    diff --git a/net/smc/smc_core.h b/net/smc/smc_core.h
    index 4cb03e9423648..7b43a78c7f73a 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 26f8f240d9e84..b0678a417e09d 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 */
    @@ -639,6 +642,7 @@ void smc_wr_free_link(struct smc_link *lnk)
    return;
    ibdev = lnk->smcibdev->ibdev;

    + smc_wr_drain_cq(lnk);
    smc_wr_wakeup_reg_wait(lnk);
    smc_wr_wakeup_tx_wait(lnk);

    @@ -889,6 +893,7 @@ 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 a54e90a1110fd..45e9b894d3f8a 100644
    --- a/net/smc/smc_wr.h
    +++ b/net/smc/smc_wr.h
    @@ -73,6 +73,11 @@ static inline void smc_wr_tx_link_put(struct smc_link *link)
    wake_up_all(&link->wr_tx_wait);
    }

    +static inline 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);
    +}
    +
    static inline void smc_wr_wakeup_tx_wait(struct smc_link *lnk)
    {
    wake_up_all(&lnk->wr_tx_wait);
    --
    2.35.1


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