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IB/hfi1: Close race condition on user context disable and close

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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

Use the appropriate kref API to verify access.

Reorder context cleanup to ensure context removal before cleanup occurs
correctly.

Cc: stable@vger.kernel.org # v4.14.0+
Fixes: f683c80ca6 ("IB/hfi1: Resolve kernel panics by reference counting receive contexts")
Reviewed-by: Mike Marciniszyn <mike.marciniszyn@intel.com>
Signed-off-by: Michael J. Ruhl <michael.j.ruhl@intel.com>
Signed-off-by: Dennis Dalessandro <dennis.dalessandro@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
This commit is contained in:
Michael J. Ruhl 2019-02-26 08:45:35 -08:00 committed by Jason Gunthorpe
parent 0c507d8f84
commit bc5add0976
2 changed files with 10 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
drivers/infiniband/hw/hfi1/hfi.h
View File

@ -1455,7 +1455,7 @@ void hfi1_init_pportdata(struct pci_dev *pdev, struct hfi1_pportdata *ppd,
struct hfi1_devdata *dd, u8 hw_pidx, u8 port);
void hfi1_free_ctxtdata(struct hfi1_devdata *dd, struct hfi1_ctxtdata *rcd);
int hfi1_rcd_put(struct hfi1_ctxtdata *rcd);
void hfi1_rcd_get(struct hfi1_ctxtdata *rcd);
int hfi1_rcd_get(struct hfi1_ctxtdata *rcd);
struct hfi1_ctxtdata *hfi1_rcd_get_by_index_safe(struct hfi1_devdata *dd,
u16 ctxt);
struct hfi1_ctxtdata *hfi1_rcd_get_by_index(struct hfi1_devdata *dd, u16 ctxt);

14
drivers/infiniband/hw/hfi1/init.c
View File

@ -214,12 +214,12 @@ 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);
}
@ -242,10 +242,13 @@ int hfi1_rcd_put(struct hfi1_ctxtdata *rcd)
* @rcd: pointer to an initialized rcd data structure
*
* Use this to get a reference after the init.
*
* Return : reflect kref_get_unless_zero(), which returns non-zero on
* increment, otherwise 0.
*/
void hfi1_rcd_get(struct hfi1_ctxtdata *rcd)
int hfi1_rcd_get(struct hfi1_ctxtdata *rcd)
{
kref_get(&rcd->kref);
return kref_get_unless_zero(&rcd->kref);
}
/**
@ -325,7 +328,8 @@ 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 (!hfi1_rcd_get(rcd))
rcd = NULL;
}
spin_unlock_irqrestore(&dd->uctxt_lock, flags);