diff options
| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-05 16:26:00 -0800 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2018-01-06 09:32:07 -0700 |
| commit | ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 (patch) | |
| tree | f581ac94d3f2c1e2059e04c392788b0ad4119ba8 | |
| parent | cbf3a95924d515c1883aec2322fec277e4726134 (diff) | |
loop: fix concurrent lo_open/lo_release
范龙飞 reports that KASAN can report a use-after-free in __lock_acquire.
The reason is due to insufficient serialization in lo_release(), which
will continue to use the loop device even after it has decremented the
lo_refcnt to zero.
In the meantime, another process can come in, open the loop device
again as it is being shut down. Confusion ensues.
Reported-by: 范龙飞 <long7573@126.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
| -rw-r--r-- | drivers/block/loop.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index bc8e61506968..d5fe720cf149 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1581,9 +1581,8 @@ out: return err; } -static void lo_release(struct gendisk *disk, fmode_t mode) +static void __lo_release(struct loop_device *lo) { - struct loop_device *lo = disk->private_data; int err; if (atomic_dec_return(&lo->lo_refcnt)) @@ -1610,6 +1609,13 @@ static void lo_release(struct gendisk *disk, fmode_t mode) mutex_unlock(&lo->lo_ctl_mutex); } +static void lo_release(struct gendisk *disk, fmode_t mode) +{ + mutex_lock(&loop_index_mutex); + __lo_release(disk->private_data); + mutex_unlock(&loop_index_mutex); +} + static const struct block_device_operations lo_fops = { .owner = THIS_MODULE, .open = lo_open, |