[LTP] [PATCH] tcindex01: Simplify test

[Martin Doucha]

The bug can be reproduced simply by adding, removing and adding again
the same tcindex traffic filter. If the bug is present, the attempt
to add the removed filter again will fail with EEXIST error.

Signed-off-by: Martin Doucha <mdoucha@suse.cz>
---

This change makes the test much faster by removing usleep() call and also
allows reliably reproducing the bug on kernels v4.x.

 testcases/cve/tcindex01.c | 37 ++++++++++++-------------------------
 1 file changed, 12 insertions(+), 25 deletions(-)

diff --git a/testcases/cve/tcindex01.c b/testcases/cve/tcindex01.c
index 9bd7de9dd..eb1f01109 100644
--- a/testcases/cve/tcindex01.c
+++ b/testcases/cve/tcindex01.c
@@ -84,31 +84,18 @@ static void setup(void)
 
 static void run(void)
 {
-	unsigned int i;
-
-	for (i = 0; i < 100; i++) {
-		NETDEV_ADD_QDISC(DEVNAME, AF_UNSPEC, TC_H_ROOT, qd_handle,
-			"htb", qd_config);
-		NETDEV_ADD_TRAFFIC_CLASS(DEVNAME, qd_handle, clsid, "htb",
-			cls_config);
-		NETDEV_ADD_TRAFFIC_FILTER(DEVNAME, qd_handle, 10, ETH_P_IP, 1,
-			"tcindex", f_config);
-		NETDEV_REMOVE_TRAFFIC_FILTER(DEVNAME, qd_handle, 10, ETH_P_IP,
-			1, "tcindex");
-
-		/* Wait at least one jiffy for use-after-free */
-		usleep(10000);
-
-		NETDEV_REMOVE_QDISC(DEVNAME, AF_UNSPEC, TC_H_ROOT, qd_handle,
-			"htb");
-	}
-
-	if (tst_taint_check()) {
-		tst_res(TFAIL, "Kernel is vulnerable");
-		return;
-	}
-
-	tst_res(TPASS, "Nothing bad happened (yet)");
+	NETDEV_ADD_QDISC(DEVNAME, AF_UNSPEC, TC_H_ROOT, qd_handle, "htb",
+		qd_config);
+	NETDEV_ADD_TRAFFIC_CLASS(DEVNAME, qd_handle, clsid, "htb", cls_config);
+	NETDEV_ADD_TRAFFIC_FILTER(DEVNAME, qd_handle, 10, ETH_P_IP, 1,
+		"tcindex", f_config);
+	NETDEV_REMOVE_TRAFFIC_FILTER(DEVNAME, qd_handle, 10, ETH_P_IP,
+		1, "tcindex");
+	tst_res(TINFO, "Trying to add removed tcindex filter again...");
+	NETDEV_ADD_TRAFFIC_FILTER(DEVNAME, qd_handle, 10, ETH_P_IP, 1,
+		"tcindex", f_config);
+	NETDEV_REMOVE_QDISC(DEVNAME, AF_UNSPEC, TC_H_ROOT, qd_handle, "htb");
+	tst_res(TPASS, "Removing tcindex filter works correctly");
 }
 
 static void cleanup(void)
-- 
2.41.0