[PATCH tip/core/rcu 8/9] locktorture: Fix potential memory leak with rw lock test

From: Paul E. McKenney
Date: Sat Jan 14 2017 - 04:26:14 EST


From: Yang Shi <yang.shi@xxxxxxxxxx>

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.

Signed-off-by: Yang Shi <yang.shi@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
kernel/locking/locktorture.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c
index f8c5af52a131..d3de04b12f8c 100644
--- a/kernel/locking/locktorture.c
+++ b/kernel/locking/locktorture.c
@@ -780,6 +780,10 @@ 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);
+
end:
torture_cleanup_end();
}
@@ -924,6 +928,8 @@ 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;
}
--
2.5.2