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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2018-01-05 16:26:00 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-02-03 17:05:33 +0100 |
| commit | 56bc086358cac1a2949783646eabd57447b9d672 (patch) | |
| tree | 418b8b120580ce6ec0e82cab2d7ac99d591bca29 /drivers/block | |
| parent | 6c6f924f9c6294944ee6efb1bbd8cdb853582e50 (diff) | |
| download | linux-rt-56bc086358cac1a2949783646eabd57447b9d672.tar.gz | |
loop: fix concurrent lo_open/lo_release
commit ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 upstream.
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>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/block')
| -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 24d6cefceb32..402254d26247 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1558,9 +1558,8 @@ 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)) @@ -1586,6 +1585,13 @@ 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, |