From cb4644cac4a2797afc847e6c92736664d4b0ea34 Mon Sep 17 00:00:00 2001 From: Jens Axboe Date: Wed, 10 Nov 2010 14:36:25 +0100 Subject: [PATCH] bio: take care not overflow page count when mapping/copying user data 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 Cc: stable@kernel.org Signed-off-by: Jens Axboe --- fs/bio.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/fs/bio.c b/fs/bio.c index 8317a2c..4bd454f 100644 --- a/fs/bio.c +++ b/fs/bio.c @@ -834,6 +834,12 @@ struct bio *bio_copy_user_iov(struct request_queue *q, 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; } @@ -962,6 +968,12 @@ static struct bio *__bio_map_user_iov(struct request_queue *q, 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 @@ -989,7 +1001,7 @@ static struct bio *__bio_map_user_iov(struct request_queue *q, 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) { -- 2.7.4