diff options
| author | Lizhi Xu <lizhi.xu@windriver.com> | 2025-04-28 22:36:26 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2025-05-18 08:24:56 +0200 |
| commit | 184b147b9f7f07577567a80fcc9314f2bd0b0b00 (patch) | |
| tree | 8ffbef47d162cf13ef969da9130c6d6a49fb7304 | |
| parent | a781ffe410d83fa8092d30d53f583d0ce8732a7b (diff) | |
loop: Add sanity check for read/write_iter
[ Upstream commit f5c84eff634ba003326aa034c414e2a9dcb7c6a7 ]
Some file systems do not support read_iter/write_iter, such as selinuxfs
in this issue.
So before calling them, first confirm that the interface is supported and
then call it.
It is releavant in that vfs_iter_read/write have the check, and removal
of their used caused szybot to be able to hit this issue.
Fixes: f2fed441c69b ("loop: stop using vfs_iter__{read,write} for buffered I/O")
Reported-by: syzbot+6af973a3b8dfd2faefdc@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6af973a3b8dfd2faefdc
Signed-off-by: Lizhi Xu <lizhi.xu@windriver.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250428143626.3318717-1-lizhi.xu@windriver.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | drivers/block/loop.c | 23 |
1 files changed, 23 insertions, 0 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index e083099a01e2..6bd44ec2c9b1 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -501,6 +501,17 @@ static void loop_assign_backing_file(struct loop_device *lo, struct file *file) lo->old_gfp_mask & ~(__GFP_IO | __GFP_FS)); } +static int loop_check_backing_file(struct file *file) +{ + if (!file->f_op->read_iter) + return -EINVAL; + + if ((file->f_mode & FMODE_WRITE) && !file->f_op->write_iter) + return -EINVAL; + + return 0; +} + /* * loop_change_fd switched the backing store of a loopback device to * a new file. This is useful for operating system installers to free up @@ -521,6 +532,10 @@ static int loop_change_fd(struct loop_device *lo, struct block_device *bdev, if (!file) return -EBADF; + error = loop_check_backing_file(file); + if (error) + return error; + /* suppress uevents while reconfiguring the device */ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1); @@ -953,6 +968,14 @@ static int loop_configure(struct loop_device *lo, blk_mode_t mode, if (!file) return -EBADF; + + if ((mode & BLK_OPEN_WRITE) && !file->f_op->write_iter) + return -EINVAL; + + error = loop_check_backing_file(file); + if (error) + return error; + is_loop = is_loop_device(file); /* This is safe, since we have a reference from open(). */ |