| From | Andi Kleen <> | Subject | [PATCH] [128/223] bio: take care not overflow page count when mapping/copying user data | Date | Mon, 13 Dec 2010 00:47:10 +0100 (CET) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ 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> Signed-off-by: Andi Kleen <ak@linux.intel.com>
--- fs/bio.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-)
Index: linux/fs/bio.c =================================================================== --- linux.orig/fs/bio.c +++ linux/fs/bio.c @@ -834,6 +834,12 @@ 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; } @@ -961,6 +967,12 @@ 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 @@ -988,7 +1000,7 @@ 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) {
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