[PATCH 1/3] IB: Fix race in sa_query

[Roland Dreier <rolandd@cisco.com>]

Use a copy of the id we'll return to the consumer so that we don't
dereference query->sa_query after calling send_mad().  A completion
may occur very quickly and end up freeing the query before we get to
do anything after send_mad().

Signed-off-by: Roland Dreier <rolandd@cisco.com>

---

 drivers/infiniband/core/sa_query.c |   18 +++++++++++++-----
 1 files changed, 13 insertions(+), 5 deletions(-)



--- linux-export2.orig/drivers/infiniband/core/sa_query.c	2005-06-23 13:16:25.000000000 -0700
+++ linux-export2/drivers/infiniband/core/sa_query.c	2005-06-24 14:49:43.592455970 -0700
@@ -507,7 +507,13 @@
 		spin_unlock_irqrestore(&idr_lock, flags);
 	}
 
-	return ret;
+	/*
+	 * It's not safe to dereference query any more, because the
+	 * send may already have completed and freed the query in
+	 * another context.  So use wr.wr_id, which has a copy of the
+	 * query's id.
+	 */
+	return ret ? ret : wr.wr_id;
 }
 
 static void ib_sa_path_rec_callback(struct ib_sa_query *sa_query,
@@ -598,14 +604,15 @@
 		rec, query->sa_query.mad->data);
 
 	*sa_query = &query->sa_query;
+
 	ret = send_mad(&query->sa_query, timeout_ms);
-	if (ret) {
+	if (ret < 0) {
 		*sa_query = NULL;
 		kfree(query->sa_query.mad);
 		kfree(query);
 	}
 
-	return ret ? ret : query->sa_query.id;
+	return ret;
 }
 EXPORT_SYMBOL(ib_sa_path_rec_get);
 
@@ -674,14 +681,15 @@
 		rec, query->sa_query.mad->data);
 
 	*sa_query = &query->sa_query;
+
 	ret = send_mad(&query->sa_query, timeout_ms);
-	if (ret) {
+	if (ret < 0) {
 		*sa_query = NULL;
 		kfree(query->sa_query.mad);
 		kfree(query);
 	}
 
-	return ret ? ret : query->sa_query.id;
+	return ret;
 }
 EXPORT_SYMBOL(ib_sa_mcmember_rec_query);
 
-
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