linux-kernel - [PATCH v3 07/33] radix tree test suite: iteration test misuses RCU

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Mon, 28 Nov 2016 13:50:11 -0800
From:   Matthew Wilcox <mawilcox@...uxonhyperv.com>
To:     linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Konstantin Khlebnikov <koct9i@...il.com>,
        Ross Zwisler <ross.zwisler@...ux.intel.com>
Cc:     Matthew Wilcox <mawilcox@...rosoft.com>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>
Subject: [PATCH v3 07/33] radix tree test suite: iteration test misuses RCU

From: Matthew Wilcox <mawilcox@...rosoft.com>

Each thread needs to register itself with RCU, otherwise the reading
thread's read lock has no effect and the freeing thread will free the
memory in the tree without waiting for the read lock to be dropped.

Signed-off-by: Matthew Wilcox <mawilcox@...rosoft.com>
---
 tools/testing/radix-tree/iteration_check.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/tools/testing/radix-tree/iteration_check.c b/tools/testing/radix-tree/iteration_check.c
index 11d570c..df71cb8 100644
--- a/tools/testing/radix-tree/iteration_check.c
+++ b/tools/testing/radix-tree/iteration_check.c
@@ -29,6 +29,8 @@ static void *add_entries_fn(void *arg)
 {
 	int pgoff;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		for (pgoff = 0; pgoff < 100; pgoff++) {
 			pthread_mutex_lock(&tree_lock);
@@ -38,6 +40,8 @@ static void *add_entries_fn(void *arg)
 		}
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -53,6 +57,8 @@ static void *tagged_iteration_fn(void *arg)
 	struct radix_tree_iter iter;
 	void **slot;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		rcu_read_lock();
 		radix_tree_for_each_tagged(slot, &tree, &iter, 0, TAG) {
@@ -72,12 +78,18 @@ static void *tagged_iteration_fn(void *arg)
 				continue;
 			}
 
-			if (rand_r(&seeds[0]) % 50 == 0)
+			if (rand_r(&seeds[0]) % 50 == 0) {
 				slot = radix_tree_iter_next(&iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
 		}
 		rcu_read_unlock();
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -93,6 +105,8 @@ static void *untagged_iteration_fn(void *arg)
 	struct radix_tree_iter iter;
 	void **slot;
 
+	rcu_register_thread();
+
 	while (!test_complete) {
 		rcu_read_lock();
 		radix_tree_for_each_slot(slot, &tree, &iter, 0) {
@@ -112,12 +126,18 @@ static void *untagged_iteration_fn(void *arg)
 				continue;
 			}
 
-			if (rand_r(&seeds[1]) % 50 == 0)
+			if (rand_r(&seeds[1]) % 50 == 0) {
 				slot = radix_tree_iter_next(&iter);
+				rcu_read_unlock();
+				rcu_barrier();
+				rcu_read_lock();
+			}
 		}
 		rcu_read_unlock();
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
@@ -127,6 +147,8 @@ static void *untagged_iteration_fn(void *arg)
  */
 static void *remove_entries_fn(void *arg)
 {
+	rcu_register_thread();
+
 	while (!test_complete) {
 		int pgoff;
 
@@ -137,6 +159,8 @@ static void *remove_entries_fn(void *arg)
 		pthread_mutex_unlock(&tree_lock);
 	}
 
+	rcu_unregister_thread();
+
 	return NULL;
 }
 
-- 
2.10.2