RDMA/iwcm: Don't touch cm_id after deref in rem_ref

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rem_ref() calls iwcm_deref_id(), which will wake up any blockers on
cm_id_priv->destroy_comp if the refcnt hits 0.  That will unblock
someone in iw_destroy_cm_id() which will free the cmid.  If that
happens before rem_ref() calls test_bit(IWCM_F_CALLBACK_DESTROY,
&cm_id_priv->flags), then the test_bit() will touch freed memory.

The fix is to read the bit first, then deref.  We should never be in
iw_destroy_cm_id() with IWCM_F_CALLBACK_DESTROY set, and there is a
BUG_ON() to make sure of that.

Signed-off-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>

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Steve Wise 2013-11-21 15:40:14 -06:00 • committed by Roland Dreier

parent 374b105797

commit 6b59ba609b

1 changed files with 9 additions and 2 deletions

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11

drivers/infiniband/core/iwcm.c

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