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authorChristoph Hellwig <hch@lst.de>2020-09-01 11:59:41 +0200
committerJens Axboe <axboe@kernel.dk>2020-09-01 08:35:35 -0600
commit08fc1ab6d748ab1a690fd483f41e2938984ce353 (patch)
tree7e141849aad3fc830215030bb9cf0cbe081a80f1 /block/partitions
parentcafe01ef8fcb248583038e1be071383530fe355a (diff)
block: fix locking in bdev_del_partition
We need to hold the whole device bd_mutex to protect against other thread concurrently deleting out partition before we get to it, and thus causing a use after free. Fixes: cddae808aeb7 ("block: pass a hd_struct to delete_partition") Reported-by: syzbot+6448f3c229bc52b82f69@syzkaller.appspotmail.com Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'block/partitions')
-rw-r--r--block/partitions/core.c27
1 files changed, 13 insertions, 14 deletions
diff --git a/block/partitions/core.c b/block/partitions/core.c
index 5a18c8edabbc..5b4869c08fb3 100644
--- a/block/partitions/core.c
+++ b/block/partitions/core.c
@@ -532,19 +532,20 @@ int bdev_add_partition(struct block_device *bdev, int partno,
int bdev_del_partition(struct block_device *bdev, int partno)
{
struct block_device *bdevp;
- struct hd_struct *part;
- int ret = 0;
-
- part = disk_get_part(bdev->bd_disk, partno);
- if (!part)
- return -ENXIO;
+ struct hd_struct *part = NULL;
+ int ret;
- ret = -ENOMEM;
- bdevp = bdget(part_devt(part));
+ bdevp = bdget_disk(bdev->bd_disk, partno);
if (!bdevp)
- goto out_put_part;
+ return -ENOMEM;
mutex_lock(&bdevp->bd_mutex);
+ mutex_lock_nested(&bdev->bd_mutex, 1);
+
+ ret = -ENXIO;
+ part = disk_get_part(bdev->bd_disk, partno);
+ if (!part)
+ goto out_unlock;
ret = -EBUSY;
if (bdevp->bd_openers)
@@ -553,16 +554,14 @@ int bdev_del_partition(struct block_device *bdev, int partno)
sync_blockdev(bdevp);
invalidate_bdev(bdevp);
- mutex_lock_nested(&bdev->bd_mutex, 1);
delete_partition(bdev->bd_disk, part);
- mutex_unlock(&bdev->bd_mutex);
-
ret = 0;
out_unlock:
+ mutex_unlock(&bdev->bd_mutex);
mutex_unlock(&bdevp->bd_mutex);
bdput(bdevp);
-out_put_part:
- disk_put_part(part);
+ if (part)
+ disk_put_part(part);
return ret;
}