linux-kernel - [PATCH v2] block: fix memory leak for elevator on add

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Date:   Sat, 22 Oct 2022 10:16:15 +0800
From:   Yu Kuai <yukuai1@...weicloud.com>
To:     axboe@...nel.dk, hch@....de, ming.lei@...hat.com
Cc:     linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        yukuai3@...wei.com, yukuai1@...weicloud.com, yi.zhang@...wei.com
Subject: [PATCH v2] block: fix memory leak for elevator on add_disk failure

From: Yu Kuai <yukuai3@...wei.com>

The default elevator is allocated in the beginning of device_add_disk(),
however, it's not freed in the following error path.

Fixes: 50e34d78815e ("block: disable the elevator int del_gendisk")
Signed-off-by: Yu Kuai <yukuai3@...wei.com>
Reviewed-by: Christoph Hellwig <hch@....de>
---
Changes in v2:
 - fix wrong fix tag
 - add review tag

 block/genhd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/block/genhd.c b/block/genhd.c
index b3d04e79e854..fea319c8f99e 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -437,9 +437,10 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 	 * Otherwise just allocate the device numbers for both the whole device
 	 * and all partitions from the extended dev_t space.
 	 */
+	ret = -EINVAL;
 	if (disk->major) {
 		if (WARN_ON(!disk->minors))
-			return -EINVAL;
+			goto out_exit_elevator;
 
 		if (disk->minors > DISK_MAX_PARTS) {
 			pr_err("block: can't allocate more than %d partitions\n",
@@ -447,14 +448,14 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 			disk->minors = DISK_MAX_PARTS;
 		}
 		if (disk->first_minor + disk->minors > MINORMASK + 1)
-			return -EINVAL;
+			goto out_exit_elevator;
 	} else {
 		if (WARN_ON(disk->minors))
-			return -EINVAL;
+			goto out_exit_elevator;
 
 		ret = blk_alloc_ext_minor();
 		if (ret < 0)
-			return ret;
+			goto out_exit_elevator;
 		disk->major = BLOCK_EXT_MAJOR;
 		disk->first_minor = ret;
 	}
@@ -571,6 +572,9 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
 out_free_ext_minor:
 	if (disk->major == BLOCK_EXT_MAJOR)
 		blk_free_ext_minor(disk->first_minor);
+out_exit_elevator:
+	if (disk->queue->elevator)
+		elevator_exit(disk->queue);
 	return ret;
 }
 EXPORT_SYMBOL(device_add_disk);
-- 
2.31.1