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Subject[PATCH 4.17 132/220] scsi: scsi_debug: Fix memory leak on module unload
Date
4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Luis Henriques <lhenriques@suse.com>

commit 52ab9768f723823a71dc659f0fad803a90f80236 upstream.

Since commit 80c49563e250 ("scsi: scsi_debug: implement IMMED bit") there
are long delays in F_SYNC_DELAY and F_SSU_DELAY. This can cause a memory
leak in schedule_resp(), which can be invoked while unloading the
scsi_debug module: free_all_queued() had already freed all sd_dp and
schedule_resp will alloc a new one, which will never get freed. Here's the
kmemleak report while running xfstests generic/350:

unreferenced object 0xffff88007d752b00 (size 128):
comm "rmmod", pid 26940, jiffies 4295816945 (age 7.588s)
hex dump (first 32 bytes):
00 2b 75 7d 00 88 ff ff 00 00 00 00 00 00 00 00 .+u}............
00 00 00 00 00 00 00 00 8e 31 a2 34 5f 03 00 00 .........1.4_...
backtrace:
[<000000002abd83d0>] 0xffffffffa000705e
[<000000004c063fda>] scsi_dispatch_cmd+0xc7/0x1a0
[<000000000c119a00>] scsi_request_fn+0x251/0x550
[<000000009de0c736>] __blk_run_queue+0x3f/0x60
[<000000001c4453c8>] blk_execute_rq_nowait+0x98/0xd0
[<00000000d17ec79f>] blk_execute_rq+0x3a/0x50
[<00000000a7654b6e>] scsi_execute+0x113/0x250
[<00000000fd78f7cd>] sd_sync_cache+0x95/0x160
[<0000000024dacb14>] sd_shutdown+0x9b/0xd0
[<00000000e9101710>] sd_remove+0x5f/0xb0
[<00000000c43f0d63>] device_release_driver_internal+0x13c/0x1f0
[<00000000e8ad57b6>] bus_remove_device+0xe9/0x160
[<00000000713a7b8a>] device_del+0x120/0x320
[<00000000e5db670c>] __scsi_remove_device+0x115/0x150
[<00000000eccbef30>] scsi_forget_host+0x20/0x60
[<00000000cd5a0738>] scsi_remove_host+0x6d/0x120

Cc: stable@vger.kernel.org # v4.17+
Signed-off-by: Luis Henriques <lhenriques@suse.com>
Acked-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/scsi/scsi_debug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/scsi/scsi_debug.c
+++ b/drivers/scsi/scsi_debug.c
@@ -5506,9 +5506,9 @@ static void __exit scsi_debug_exit(void)
int k = sdebug_add_host;

stop_all_queued();
- free_all_queued();
for (; k; k--)
sdebug_remove_adapter();
+ free_all_queued();
driver_unregister(&sdebug_driverfs_driver);
bus_unregister(&pseudo_lld_bus);
root_device_unregister(pseudo_primary);

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