From 8535639810e578960233ad39def3ac2157b0c3ec Mon Sep 17 00:00:00 2001 From: Richard Weinberger Date: Wed, 2 Nov 2011 13:17:27 +0100 Subject: [PATCH] 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: Richard Weinberger CC: stable@kernel.org --- arch/um/drivers/ubd_kern.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/um/drivers/ubd_kern.c b/arch/um/drivers/ubd_kern.c index b3c854523e6c..944453a3ec99 100644 --- a/arch/um/drivers/ubd_kern.c +++ b/arch/um/drivers/ubd_kern.c @@ -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; + + goto out; + } - file = ubd_dev->cow.file ? ubd_dev->cow.file : ubd_dev->file; + 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, §or_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); } -- 2.39.2