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    Subject[PATCH 5.16 0334/1039] block: fix error unwinding in device_add_disk
    Date
    From: Christoph Hellwig <hch@lst.de>

    [ Upstream commit 99d8690aae4b2f0d1d90075de355ac087f820a66 ]

    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: 83cbce9574462c6b ("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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    block/genhd.c | 13 ++++++-------
    1 file changed, 6 insertions(+), 7 deletions(-)

    diff --git a/block/genhd.c b/block/genhd.c
    index 30362aeacac4b..596e43764846b 100644
    --- a/block/genhd.c
    +++ b/block/genhd.c
    @@ -437,10 +437,6 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
    disk->flags |= GENHD_FL_EXT_DEVT;
    }

    - ret = disk_alloc_events(disk);
    - if (ret)
    - goto out_free_ext_minor;
    -
    /* delay uevents, until we scanned partition table */
    dev_set_uevent_suppress(ddev, 1);

    @@ -451,7 +447,12 @@ int __must_check device_add_disk(struct device *parent, struct gendisk *disk,
    ddev->devt = MKDEV(disk->major, disk->first_minor);
    ret = device_add(ddev);
    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) {
    ret = sysfs_create_link(block_depr, &ddev->kobj,
    kobject_name(&ddev->kobj));
    @@ -539,8 +540,6 @@ out_del_block_link:
    sysfs_remove_link(block_depr, dev_name(ddev));
    out_device_del:
    device_del(ddev);
    -out_disk_release_events:
    - disk_release_events(disk);
    out_free_ext_minor:
    if (disk->major == BLOCK_EXT_MAJOR)
    blk_free_ext_minor(disk->first_minor);
    --
    2.34.1


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