linux-stable.git/drivers/block/loop.c, branch v4.14.95

loop: drop caches if offset or block_size are changed

2019-01-23T07:09:51+00:00

commit 5db470e229e22b7eda6e23b5566e532c96fb5bc3 upstream.

If we don't drop caches used in old offset or block_size, we can get old data
from new offset/block_size, which gives unexpected data to user.

For example, Martijn found a loopback bug in the below scenario.
1) LOOP_SET_FD loads first two pages on loop file
2) LOOP_SET_STATUS64 changes the offset on the loop file
3) mount is failed due to the cached pages having wrong superblock

Cc: Jens Axboe 
Cc: linux-block@vger.kernel.org
Reported-by: Martijn Coenen 
Reviewed-by: Bart Van Assche 
Signed-off-by: Jaegeuk Kim 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: Fix double mutex_unlock(&loop_ctl_mutex) in loop_control_ioctl()

2019-01-23T07:09:51+00:00

commit 628bd85947091830a8c4872adfd5ed1d515a9cf2 upstream.

Commit 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex") forgot to
remove mutex_unlock(&loop_ctl_mutex) from loop_control_ioctl() when
replacing loop_index_mutex with loop_ctl_mutex.

Fixes: 0a42e99b58a20883 ("loop: Get rid of loop_index_mutex")
Reported-by: syzbot 
Reviewed-by: Ming Lei 
Reviewed-by: Jan Kara 
Signed-off-by: Tetsuo Handa 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: Get rid of loop_index_mutex

2019-01-23T07:09:51+00:00

commit 0a42e99b58a208839626465af194cfe640ef9493 upstream.

Now that loop_ctl_mutex is global, just get rid of loop_index_mutex as
there is no good reason to keep these two separate and it just
complicates the locking.

Signed-off-by: Jan Kara 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: Fold __loop_release into loop_release

2019-01-23T07:09:51+00:00

commit 967d1dc144b50ad005e5eecdfadfbcfb399ffff6 upstream.

__loop_release() has a single call site. Fold it there. This is
currently not a huge win but it will make following replacement of
loop_index_mutex more obvious.

Signed-off-by: Jan Kara 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block/loop: Use global lock for ioctl() operation.

2019-01-23T07:09:51+00:00

commit 310ca162d779efee8a2dc3731439680f3e9c1e86 upstream.

syzbot is reporting NULL pointer dereference [1] which is caused by
race condition between ioctl(loop_fd, LOOP_CLR_FD, 0) versus
ioctl(other_loop_fd, LOOP_SET_FD, loop_fd) due to traversing other
loop devices at loop_validate_file() without holding corresponding
lo->lo_ctl_mutex locks.

Since ioctl() request on loop devices is not frequent operation, we don't
need fine grained locking. Let's use global lock in order to allow safe
traversal at loop_validate_file().

Note that syzbot is also reporting circular locking dependency between
bdev->bd_mutex and lo->lo_ctl_mutex [2] which is caused by calling
blkdev_reread_part() with lock held. This patch does not address it.

[1] https://syzkaller.appspot.com/bug?id=f3cfe26e785d85f9ee259f385515291d21bd80a3
[2] https://syzkaller.appspot.com/bug?id=bf154052f0eea4bc7712499e4569505907d15889

Signed-off-by: Tetsuo Handa 
Reported-by: syzbot 
Reviewed-by: Jan Kara 
Signed-off-by: Jan Kara 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

block/loop: Don't grab "struct file" for vfs_getattr() operation.

2019-01-23T07:09:51+00:00

commit b1ab5fa309e6c49e4e06270ec67dd7b3e9971d04 upstream.

vfs_getattr() needs "struct path" rather than "struct file".
Let's use path_get()/path_put() rather than get_file()/fput().

Signed-off-by: Tetsuo Handa 
Reviewed-by: Jan Kara 
Signed-off-by: Jan Kara 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: remember whether sysfs_create_group() was done

2018-07-17T09:39:33+00:00

commit d3349b6b3c373ac1fbfb040b810fcee5e2adc7e0 upstream.

syzbot is hitting WARN() triggered by memory allocation fault
injection [1] because loop module is calling sysfs_remove_group()
when sysfs_create_group() failed.
Fix this by remembering whether sysfs_create_group() succeeded.

[1] https://syzkaller.appspot.com/bug?id=3f86c0edf75c86d2633aeb9dd69eccc70bc7e90b

Signed-off-by: Tetsuo Handa 
Reported-by: syzbot 
Reviewed-by: Greg Kroah-Hartman 

Renamed sysfs_ready -> sysfs_inited.

Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: add recursion validation to LOOP_CHANGE_FD

2018-07-17T09:39:32+00:00

commit d2ac838e4cd7e5e9891ecc094d626734b0245c99 upstream.

Refactor the validation code used in LOOP_SET_FD so it is also used in
LOOP_CHANGE_FD.  Otherwise it is possible to construct a set of loop
devices that all refer to each other.  This can lead to a infinite
loop in starting with "while (is_loop_device(f)) .." in loop_set_fd().

Fix this by refactoring out the validation code and using it for
LOOP_CHANGE_FD as well as LOOP_SET_FD.

Reported-by: syzbot+4349872271ece473a7c91190b68b4bac7c5dbc87@syzkaller.appspotmail.com
Reported-by: syzbot+40bd32c4d9a3cc12a339@syzkaller.appspotmail.com
Reported-by: syzbot+769c54e66f994b041be7@syzkaller.appspotmail.com
Reported-by: syzbot+0a89a9ce473936c57065@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: fix LOOP_GET_STATUS lock imbalance

2018-05-25T14:17:35+00:00

commit bdac616db9bbadb90b7d6a406144571015e138f7 upstream.

Commit 2d1d4c1e591f made loop_get_status() drop lo_ctx_mutex before
returning, but the loop_get_status_old(), loop_get_status64(), and
loop_get_status_compat() wrappers don't call loop_get_status() if the
passed argument is NULL. The callers expect that the lock is dropped, so
make sure we drop it in that case, too.

Reported-by: syzbot+31e8daa8b3fc129e75f2@syzkaller.appspotmail.com
Fixes: 2d1d4c1e591f ("loop: don't call into filesystem while holding lo_ctl_mutex")
Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman

loop: don't call into filesystem while holding lo_ctl_mutex

2018-05-25T14:17:34+00:00

commit 2d1d4c1e591fd40bd7dafd868a249d7d00e215d5 upstream.

We hit an issue where a loop device on NFS was stuck in
loop_get_status() doing vfs_getattr() after the NFS server died, which
caused a pile-up of uninterruptible processes waiting on lo_ctl_mutex.
There's no reason to hold this lock while we wait on the filesystem;
let's drop it so that other processes can do their thing. We need to
grab a reference on lo_backing_file while we use it, and we can get rid
of the check on lo_device, which has been unnecessary since commit
a34c0ae9ebd6 ("[PATCH] loop: remove the bio remapping capability") in
the linux-history tree.

Signed-off-by: Omar Sandoval 
Signed-off-by: Jens Axboe 
Signed-off-by: Greg Kroah-Hartman