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| author | Andrey Ryabinin <aryabinin@virtuozzo.com> | 2016-08-23 17:55:31 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@fb.com> | 2016-08-25 16:38:26 +0200 |
| commit | 5bb53c0fb8e0fc2e34287d5d0fcadc784de913e1 (patch) | |
| tree | 21251b388aec1c09a072ddb489abff447f2c52d6 /fs/block_dev.c | |
| parent | blk-mq: improve warning for running a queue on the wrong CPU (diff) | |
| download | linux-5bb53c0fb8e0fc2e34287d5d0fcadc784de913e1.tar.xz linux-5bb53c0fb8e0fc2e34287d5d0fcadc784de913e1.zip | |
fs/block_dev: fix potential NULL ptr deref in freeze_bdev()
Calling freeze_bdev() twice on the same block device without mounted
filesystem get_super() will return NULL, which will lead to NULL-ptr
dereference later in drop_super().
Check get_super() result to fix that.
Note, that this is a purely theoretical issue. We have only 3
freeze_bdev() callers. 2 of them are in filesystem code and used on a
device with mounted fs. The third one in lock_fs() has protection in
upper-layer code against freezing block device the second time without
thawing it first.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Diffstat (limited to 'fs/block_dev.c')
| -rw-r--r-- | fs/block_dev.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/block_dev.c b/fs/block_dev.c index e17bdbdfe9b1..08ae99343d92 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -249,7 +249,8 @@ struct super_block *freeze_bdev(struct block_device *bdev) * thaw_bdev drops it. */ sb = get_super(bdev); - drop_super(sb); + if (sb) + drop_super(sb); mutex_unlock(&bdev->bd_fsfreeze_mutex); return sb; } |