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IB/rdmavt: Fix concurrency panics in QP post_send and modify to error

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The RC/UC code path can go through a software loopback. In this code path
the receive side QP is manipulated.

If two threads are working on the QP receive side (i.e. post_send, and
modify_qp to an error state), QP information can be corrupted.

(post_send via loopback)
  set r_sge
  loop
     update r_sge
(modify_qp)
     take r_lock
     update r_sge <---- r_sge is now incorrect
(post_send)
     update r_sge <---- crash, etc.
     ...

This can lead to one of the two following crashes:

 BUG: unable to handle kernel NULL pointer dereference at (null)
  IP:  hfi1_copy_sge+0xf1/0x2e0 [hfi1]
  PGD 8000001fe6a57067 PUD 1fd9e0c067 PMD 0
 Call Trace:
  ruc_loopback+0x49b/0xbc0 [hfi1]
  hfi1_do_send+0x38e/0x3e0 [hfi1]
  _hfi1_do_send+0x1e/0x20 [hfi1]
  process_one_work+0x17f/0x440
  worker_thread+0x126/0x3c0
  kthread+0xd1/0xe0
  ret_from_fork_nospec_begin+0x21/0x21

or:

 BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
  IP:  rvt_clear_mr_refs+0x45/0x370 [rdmavt]
  PGD 80000006ae5eb067 PUD ef15d0067 PMD 0
 Call Trace:
  rvt_error_qp+0xaa/0x240 [rdmavt]
  rvt_modify_qp+0x47f/0xaa0 [rdmavt]
  ib_security_modify_qp+0x8f/0x400 [ib_core]
  ib_modify_qp_with_udata+0x44/0x70 [ib_core]
  modify_qp.isra.23+0x1eb/0x2b0 [ib_uverbs]
  ib_uverbs_modify_qp+0xaa/0xf0 [ib_uverbs]
  ib_uverbs_write+0x272/0x430 [ib_uverbs]
  vfs_write+0xc0/0x1f0
  SyS_write+0x7f/0xf0
  system_call_fastpath+0x1c/0x21

Fix by using the appropriate locking on the receiving QP.

Fixes: 1570346153 ("IB/{hfi1, qib, rdmavt}: Move ruc_loopback to rdmavt")
Cc: <stable@vger.kernel.org> #v4.9+
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 08:45:25 -08:00 committed by Jason Gunthorpe
parent 38bbc9f038
commit d757c60eca
1 changed files with 23 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

33
drivers/infiniband/sw/rdmavt/qp.c
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@ -2790,6 +2790,18 @@ void rvt_copy_sge(struct rvt_qp *qp, struct rvt_sge_state *ss,
}
EXPORT_SYMBOL(rvt_copy_sge);
static enum ib_wc_status loopback_qp_drop(struct rvt_ibport *rvp,
struct rvt_qp *sqp)
{
rvp->n_pkt_drops++;
/*
* For RC, the requester would timeout and retry so
* shortcut the timeouts and just signal too many retries.
*/
return sqp->ibqp.qp_type == IB_QPT_RC ?
IB_WC_RETRY_EXC_ERR : IB_WC_SUCCESS;
}
/**
* ruc_loopback - handle UC and RC loopback requests
* @sqp: the sending QP
@ -2862,17 +2874,14 @@ void rvt_ruc_loopback(struct rvt_qp *sqp)
}
spin_unlock_irqrestore(&sqp->s_lock, flags);
if (!qp || !(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) ||
if (!qp) {
send_status = loopback_qp_drop(rvp, sqp);
goto serr_no_r_lock;
}
spin_lock_irqsave(&qp->r_lock, flags);
if (!(ib_rvt_state_ops[qp->state] & RVT_PROCESS_RECV_OK) ||
qp->ibqp.qp_type != sqp->ibqp.qp_type) {
rvp->n_pkt_drops++;
/*
* For RC, the requester would timeout and retry so
* shortcut the timeouts and just signal too many retries.
*/
if (sqp->ibqp.qp_type == IB_QPT_RC)
send_status = IB_WC_RETRY_EXC_ERR;
else
send_status = IB_WC_SUCCESS;
send_status = loopback_qp_drop(rvp, sqp);
goto serr;
}
@ -3030,6 +3039,7 @@ void rvt_ruc_loopback(struct rvt_qp *sqp)
wqe->wr.send_flags & IB_SEND_SOLICITED);
send_comp:
spin_unlock_irqrestore(&qp->r_lock, flags);
spin_lock_irqsave(&sqp->s_lock, flags);
rvp->n_loop_pkts++;
flush_send:
@ -3056,6 +3066,7 @@ void rvt_ruc_loopback(struct rvt_qp *sqp)
}
if (sqp->s_rnr_retry_cnt < 7)
sqp->s_rnr_retry--;
spin_unlock_irqrestore(&qp->r_lock, flags);
spin_lock_irqsave(&sqp->s_lock, flags);
if (!(ib_rvt_state_ops[sqp->state] & RVT_PROCESS_RECV_OK))
goto clr_busy;
@ -3084,6 +3095,8 @@ void rvt_ruc_loopback(struct rvt_qp *sqp)
rvt_rc_error(qp, wc.status);
serr:
spin_unlock_irqrestore(&qp->r_lock, flags);
serr_no_r_lock:
spin_lock_irqsave(&sqp->s_lock, flags);
rvt_send_complete(sqp, wqe, send_status);
if (sqp->ibqp.qp_type == IB_QPT_RC) {