| From cb4644cac4a2797afc847e6c92736664d4b0ea34 Mon Sep 17 00:00:00 2001 |
| From: Jens Axboe <jaxboe@fusionio.com> |
| Date: Wed, 10 Nov 2010 14:36:25 +0100 |
| Subject: bio: take care not overflow page count when mapping/copying user data |
| |
| From: Jens Axboe <jaxboe@fusionio.com> |
| |
| commit cb4644cac4a2797afc847e6c92736664d4b0ea34 upstream. |
| |
| If the iovec is being set up in a way that causes uaddr + PAGE_SIZE |
| to overflow, we could end up attempting to map a huge number of |
| pages. Check for this invalid input type. |
| |
| Reported-by: Dan Rosenberg <drosenberg@vsecurity.com> |
| Signed-off-by: Jens Axboe <jaxboe@fusionio.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| fs/bio.c | 14 +++++++++++++- |
| 1 file changed, 13 insertions(+), 1 deletion(-) |
| |
| --- a/fs/bio.c |
| +++ b/fs/bio.c |
| @@ -838,6 +838,12 @@ struct bio *bio_copy_user_iov(struct req |
| end = (uaddr + iov[i].iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| start = uaddr >> PAGE_SHIFT; |
| |
| + /* |
| + * Overflow, abort |
| + */ |
| + if (end < start) |
| + return ERR_PTR(-EINVAL); |
| + |
| nr_pages += end - start; |
| len += iov[i].iov_len; |
| } |
| @@ -965,6 +971,12 @@ static struct bio *__bio_map_user_iov(st |
| unsigned long end = (uaddr + len + PAGE_SIZE - 1) >> PAGE_SHIFT; |
| unsigned long start = uaddr >> PAGE_SHIFT; |
| |
| + /* |
| + * Overflow, abort |
| + */ |
| + if (end < start) |
| + return ERR_PTR(-EINVAL); |
| + |
| nr_pages += end - start; |
| /* |
| * buffer must be aligned to at least hardsector size for now |
| @@ -992,7 +1004,7 @@ static struct bio *__bio_map_user_iov(st |
| unsigned long start = uaddr >> PAGE_SHIFT; |
| const int local_nr_pages = end - start; |
| const int page_limit = cur_page + local_nr_pages; |
| - |
| + |
| ret = get_user_pages_fast(uaddr, local_nr_pages, |
| write_to_vm, &pages[cur_page]); |
| if (ret < local_nr_pages) { |
