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Subject[PATCH] workqueue: fix a memory leak in wq->lock_name
Date
The commit 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for
workqueues") introduced a memory leak as wq_free_lockdep() calls
kfree(wq->lock_name) but wq_init_lockdep() does not point wq->lock_name
to the newly allocated slab object. This can be reproduced by running
LTP fallocate04 followed by oom01 tests.

unreferenced object 0xc0000005876384d8 (size 64):
comm "fallocate04", pid 26972, jiffies 4297139141 (age 40370.480s)
hex dump (first 32 bytes):
28 77 71 5f 63 6f 6d 70 6c 65 74 69 6f 6e 29 65 (wq_completion)e
78 74 34 2d 72 73 76 2d 63 6f 6e 76 65 72 73 69 xt4-rsv-conversi
backtrace:
[<00000000cb452883>] kvasprintf+0x6c/0xe0
[<000000004654ddac>] kasprintf+0x34/0x60
[<000000001c68f311>] alloc_workqueue+0x1f8/0x6ac
[<0000000003c2ad83>] ext4_fill_super+0x23d4/0x3c80 [ext4]
[<0000000006610538>] mount_bdev+0x25c/0x290
[<00000000bcf955ec>] ext4_mount+0x28/0x50 [ext4]
[<0000000016e08fd3>] legacy_get_tree+0x4c/0xb0
[<0000000042b6a5fc>] vfs_get_tree+0x6c/0x190
[<00000000268ab022>] do_mount+0xb9c/0x1100
[<00000000698e6898>] ksys_mount+0x158/0x180
[<0000000064e391fd>] sys_mount+0x20/0x30
[<00000000ba378f12>] system_call+0x5c/0x70

Fixes: 669de8bda87b ("kernel/workqueue: Use dynamic lockdep keys for workqueues")
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Qian Cai <cai@lca.pw>
---
kernel/workqueue.c | 2 ++
1 file changed, 2 insertions(+)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index e163e7a7f5e5..ade0d47ec086 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3348,6 +3348,8 @@ static void wq_init_lockdep(struct workqueue_struct *wq)
lock_name = kasprintf(GFP_KERNEL, "%s%s", "(wq_completion)", wq->name);
if (!lock_name)
lock_name = wq->name;
+
+ wq->lock_name = lock_name;
lockdep_init_map(&wq->lockdep_map, lock_name, &wq->key, 0);
}

--
2.17.2 (Apple Git-113)
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