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Commit 85356398 authored by Richard Weinberger's avatar Richard Weinberger
Browse files

um: fix ubd cow size 



ubd_file_size() cannot use ubd_dev->cow.file because at this time
ubd_dev->cow.file is not initialized.
Therefore, ubd_file_size() will always report a wrong disk size when
COW files are used.
Reading from /dev/ubd* would crash the kernel.

We have to read the correct disk size from the COW file's backing
file.

Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
CC: stable@kernel.org
parent 0d65ede0

arch/um/drivers/ubd_kern.c

+30 −1
Original line number Diff line number Diff line
@@ -511,8 +511,37 @@ __uml_exitcall(kill_io_thread); 
static inline int ubd_file_size(struct ubd *ubd_dev, __u64 *size_out)

{

	char *file;

	int fd;

	int err;



	__u32 version;

	__u32 align;

	char *backing_file;

	time_t mtime;

	unsigned long long size;

	int sector_size;

	int bitmap_offset;



	if (ubd_dev->file && ubd_dev->cow.file) {

		file = ubd_dev->cow.file;



	file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file;

		goto out;

	}



	fd = os_open_file(ubd_dev->file, global_openflags, 0);

	if (fd < 0)

		return fd;



	err = read_cow_header(file_reader, &fd, &version, &backing_file, \

		&mtime, &size, &sector_size, &align, &bitmap_offset);

	os_close_file(fd);



	if(err == -EINVAL)

		file = ubd_dev->file;

	else

		file = backing_file;



out:

	return os_file_size(file, size_out);

}