From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dennis Dalessandro Subject: [PATCH for-rc 5/7] IB/hfi1: Close race condition on user context disable and close Date: Thu, 17 Jan 2019 12:41:54 -0800 Message-ID: <20190117204148.30826.53799.stgit@scvm10.sc.intel.com> References: <20190117203920.30826.76720.stgit@scvm10.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20190117203920.30826.76720.stgit@scvm10.sc.intel.com> Sender: stable-owner@vger.kernel.org To: jgg@ziepe.ca, dledford@redhat.com Cc: linux-rdma@vger.kernel.org, "Michael J. Ruhl" , Mike Marciniszyn , stable@vger.kernel.org List-Id: linux-rdma@vger.kernel.org From: Michael J. Ruhl When disabling and removing a receive context, it is possible for an asynchronous event (i.e IRQ) to occur. Because of this there is a race between cleaning up the context, and the context being used by the asynchronous event. cpu 0 (context cleanup) rc->ref_count-- (ref_count == 0) hfi1_rcd_free() cpu 1 (IRQ (with rcd index)) rcd_get_by_index() lock ref_count+++ <-- reference count race (WARNING) return rcd unlock cpu 0 hfi1_free_ctxtdata() <-- incorrect free location lock remove rcd from array unlock free rcd This race will cause the following WARNING trace: WARNING: CPU: 0 PID: 175027 at include/linux/kref.h:52 hfi1_rcd_get_by_index+0x84/0xa0 [hfi1] CPU: 0 PID: 175027 Comm: IMB-MPI1 Kdump: loaded Tainted: G OE ------------ 3.10.0-957.el7.x86_64 #1 Hardware name: Intel Corporation S2600KP/S2600KP, BIOS SE5C610.86B.11.01.0076.C4.111920150602 11/19/2015 Call Trace: dump_stack+0x19/0x1b __warn+0xd8/0x100 warn_slowpath_null+0x1d/0x20 hfi1_rcd_get_by_index+0x84/0xa0 [hfi1] is_rcv_urgent_int+0x24/0x90 [hfi1] general_interrupt+0x1b6/0x210 [hfi1] __handle_irq_event_percpu+0x44/0x1c0 handle_irq_event_percpu+0x32/0x80 handle_irq_event+0x3c/0x60 handle_edge_irq+0x7f/0x150 handle_irq+0xe4/0x1a0 do_IRQ+0x4d/0xf0 common_interrupt+0x162/0x162 The race can also lead to a use after free which could be similar to: general protection fault: 0000 1 SMP CPU: 71 PID: 177147 Comm: IMB-MPI1 Kdump: loaded Tainted: G W OE ------------ 3.10.0-957.el7.x86_64 #1 Hardware name: Intel Corporation S2600KP/S2600KP, BIOS SE5C610.86B.11.01.0076.C4.111920150602 11/19/2015 task: ffff9962a8098000 ti: ffff99717a508000 task.ti: ffff99717a508000 __kmalloc+0x94/0x230 Call Trace: ? hfi1_user_sdma_process_request+0x9c8/0x1250 [hfi1] hfi1_user_sdma_process_request+0x9c8/0x1250 [hfi1] hfi1_aio_write+0xba/0x110 [hfi1] do_sync_readv_writev+0x7b/0xd0 do_readv_writev+0xce/0x260 ? handle_mm_fault+0x39d/0x9b0 ? pick_next_task_fair+0x5f/0x1b0 ? sched_clock_cpu+0x85/0xc0 ? __schedule+0x13a/0x890 vfs_writev+0x35/0x60 SyS_writev+0x7f/0x110 system_call_fastpath+0x22/0x27 Introduce a context enable flag to indicate if the context is enabled. Reorder context cleanup to ensure context removal before cleanup occurs correctly. Cc: stable@vger.kernel.org # v4.14.0+ Fixes: f683c80ca68e ("IB/hfi1: Resolve kernel panics by reference counting receive contexts") Reviewed-by: Mike Marciniszyn Signed-off-by: Michael J. Ruhl Signed-off-by: Dennis Dalessandro --- drivers/infiniband/hw/hfi1/file_ops.c | 2 ++ drivers/infiniband/hw/hfi1/hfi.h | 3 ++- drivers/infiniband/hw/hfi1/init.c | 8 +++++--- 3 files changed, 9 insertions(+), 4 deletions(-) diff --git a/drivers/infiniband/hw/hfi1/file_ops.c b/drivers/infiniband/hw/hfi1/file_ops.c index c22ebc7..0ba0cf5 100644 --- a/drivers/infiniband/hw/hfi1/file_ops.c +++ b/drivers/infiniband/hw/hfi1/file_ops.c @@ -671,6 +671,8 @@ static int hfi1_file_close(struct inode *inode, struct file *fp) } spin_unlock_irqrestore(&dd->uctxt_lock, flags); + uctxt->del_pend = 1; + /* * Disable receive context and interrupt available, reset all * RcvCtxtCtrl bits to default values. diff --git a/drivers/infiniband/hw/hfi1/hfi.h b/drivers/infiniband/hw/hfi1/hfi.h index dc8ba43..ea99768 100644 --- a/drivers/infiniband/hw/hfi1/hfi.h +++ b/drivers/infiniband/hw/hfi1/hfi.h @@ -284,7 +284,8 @@ struct hfi1_ctxtdata { u16 expected_base; /* Device context index */ u8 ctxt; - + /* ctxt deletion is pending */ + u8 del_pend; /* PSM Specific fields */ /* lock protecting all Expected TID data */ struct mutex exp_mutex; diff --git a/drivers/infiniband/hw/hfi1/init.c b/drivers/infiniband/hw/hfi1/init.c index 044d9a8..d2ac3ef 100644 --- a/drivers/infiniband/hw/hfi1/init.c +++ b/drivers/infiniband/hw/hfi1/init.c @@ -215,12 +215,11 @@ static void hfi1_rcd_free(struct kref *kref) struct hfi1_ctxtdata *rcd = container_of(kref, struct hfi1_ctxtdata, kref); - hfi1_free_ctxtdata(rcd->dd, rcd); - spin_lock_irqsave(&rcd->dd->uctxt_lock, flags); rcd->dd->rcd[rcd->ctxt] = NULL; spin_unlock_irqrestore(&rcd->dd->uctxt_lock, flags); + hfi1_free_ctxtdata(rcd->dd, rcd); kfree(rcd); } @@ -326,7 +325,10 @@ struct hfi1_ctxtdata *hfi1_rcd_get_by_index(struct hfi1_devdata *dd, u16 ctxt) spin_lock_irqsave(&dd->uctxt_lock, flags); if (dd->rcd[ctxt]) { rcd = dd->rcd[ctxt]; - hfi1_rcd_get(rcd); + if (rcd->del_pend) + rcd = NULL; + else + hfi1_rcd_get(rcd); } spin_unlock_irqrestore(&dd->uctxt_lock, flags);