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block: fix error unwinding in device_add_disk

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One device_add is called disk->ev will be freed by disk_release, so we
should free it twice.  Fix this by allocating disk->ev after device_add
so that the extra local unwinding can be removed entirely.

Based on an earlier patch from Tetsuo Handa.

Reported-by: syzbot <syzbot+28a66a9fbc621c939000@syzkaller.appspotmail.com>
Tested-by: syzbot <syzbot+28a66a9fbc621c939000@syzkaller.appspotmail.com>
Fixes: 83cbce9574 ("block: add error handling for device_add_disk / add_disk")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20211221161851.788424-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Christoph Hellwig 2021-12-21 17:18:51 +01:00 committed by Jens Axboe
parent 37e11c3616
commit 99d8690aae
1 changed files with 6 additions and 7 deletions
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13
block/genhd.c
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@ -442,10 +442,6 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
disk->first_minor = ret; disk->first_minor = ret;
} }
ret = disk_alloc_events(disk);
if (ret)
goto out_free_ext_minor;
/* delay uevents, until we scanned partition table */ /* delay uevents, until we scanned partition table */
dev_set_uevent_suppress(ddev, 1); dev_set_uevent_suppress(ddev, 1);
@ -456,7 +452,12 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
ddev->devt = MKDEV(disk->major, disk->first_minor); ddev->devt = MKDEV(disk->major, disk->first_minor);
ret = device_add(ddev); ret = device_add(ddev);
if (ret) if (ret)
goto out_disk_release_events; goto out_free_ext_minor;
ret = disk_alloc_events(disk);
if (ret)
goto out_device_del;
if (!sysfs_deprecated) { if (!sysfs_deprecated) {
ret = sysfs_create_link(block_depr, &ddev->kobj, ret = sysfs_create_link(block_depr, &ddev->kobj,
kobject_name(&ddev->kobj)); kobject_name(&ddev->kobj));
@ -538,8 +539,6 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
sysfs_remove_link(block_depr, dev_name(ddev)); sysfs_remove_link(block_depr, dev_name(ddev));
out_device_del: out_device_del:
device_del(ddev); device_del(ddev);
out_disk_release_events:
disk_release_events(disk);
out_free_ext_minor: out_free_ext_minor:
if (disk->major == BLOCK_EXT_MAJOR) if (disk->major == BLOCK_EXT_MAJOR)
blk_free_ext_minor(disk->first_minor); blk_free_ext_minor(disk->first_minor);