Patch "locktorture: Fix potential memory leak with rw lock test" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

locktorture: Fix potential memory leak with rw lock test

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
locktorture-fix-potential-memory-leak-with-rw-lock-test.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Yang Shi <[email protected]>
Date: Thu, 10 Nov 2016 13:06:39 -0800
Subject: locktorture: Fix potential memory leak with rw lock test

From: Yang Shi <[email protected]>

commit f4dbba591945dc301c302672adefba9e2ec08dc5 upstream.

When running locktorture module with the below commands with kmemleak enabled:

$ modprobe locktorture torture_type=rw_lock_irq
$ rmmod locktorture

The below kmemleak got caught:

root@10:~# echo scan > /sys/kernel/debug/kmemleak
[  323.197029] kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
root@10:~# cat /sys/kernel/debug/kmemleak
unreferenced object 0xffffffc07592d500 (size 128):
  comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 c3 7b 02 00 00 00 00 00  .........{......
    00 00 00 00 00 00 00 00 d7 9b 02 00 00 00 00 00  ................
  backtrace:
    [<ffffff80081e5a88>] create_object+0x110/0x288
    [<ffffff80086c6078>] kmemleak_alloc+0x58/0xa0
    [<ffffff80081d5acc>] __kmalloc+0x234/0x318
    [<ffffff80006fa130>] 0xffffff80006fa130
    [<ffffff8008083ae4>] do_one_initcall+0x44/0x138
    [<ffffff800817e28c>] do_init_module+0x68/0x1cc
    [<ffffff800811c848>] load_module+0x1a68/0x22e0
    [<ffffff800811d340>] SyS_finit_module+0xe0/0xf0
    [<ffffff80080836f0>] el0_svc_naked+0x24/0x28
    [<ffffffffffffffff>] 0xffffffffffffffff
unreferenced object 0xffffffc07592d480 (size 128):
  comm "modprobe", pid 368, jiffies 4294924118 (age 205.824s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 3b 6f 01 00 00 00 00 00  ........;o......
    00 00 00 00 00 00 00 00 23 6a 01 00 00 00 00 00  ........#j......
  backtrace:
    [<ffffff80081e5a88>] create_object+0x110/0x288
    [<ffffff80086c6078>] kmemleak_alloc+0x58/0xa0
    [<ffffff80081d5acc>] __kmalloc+0x234/0x318
    [<ffffff80006fa22c>] 0xffffff80006fa22c
    [<ffffff8008083ae4>] do_one_initcall+0x44/0x138
    [<ffffff800817e28c>] do_init_module+0x68/0x1cc
    [<ffffff800811c848>] load_module+0x1a68/0x22e0
    [<ffffff800811d340>] SyS_finit_module+0xe0/0xf0
    [<ffffff80080836f0>] el0_svc_naked+0x24/0x28
    [<ffffffffffffffff>] 0xffffffffffffffff

It is because cxt.lwsa and cxt.lrsa don't get freed in module_exit, so free them in lock_torture_cleanup() and free writer_tasks if reader_tasks is failed at memory allocation.

---
 kernel/locking/locktorture.c |    4 ++++
 1 file changed, 4 insertions(+)

@@ -776,6 +776,8 @@ static void lock_torture_cleanup(void)
 	else
 		lock_torture_print_module_parms(cxt.cur_ops,
 						"End of test: SUCCESS");
+	kfree(cxt.lwsa);
+	kfree(cxt.lrsa);
 	torture_cleanup_end();
 }
 

@@ -917,6 +919,8 @@ static int __init lock_torture_init(void
 				       GFP_KERNEL);
 		if (reader_tasks == NULL) {
 			VERBOSE_TOROUT_ERRSTRING("reader_tasks: Out of memory");
+			kfree(writer_tasks);
+			writer_tasks = NULL;
 			firsterr = -ENOMEM;
 			goto unwind;
 		}

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/locktorture-fix-potential-memory-leak-with-rw-lock-test.patch