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| author | Jens Axboe <jaxboe@fusionio.com> | 2010-11-10 14:36:25 +0100 |
|---|---|---|
| committer | Jens Axboe <jaxboe@fusionio.com> | 2010-11-10 14:40:43 +0100 |
| commit | cb4644cac4a2797afc847e6c92736664d4b0ea34 (patch) | |
| tree | 14170d74d5040be49af14b484f252d888141a99f | |
| parent | f3f63c1c28bc861a931fac283b5bc3585efb8967 (diff) | |
| download | lwn-cb4644cac4a2797afc847e6c92736664d4b0ea34.tar.gz lwn-cb4644cac4a2797afc847e6c92736664d4b0ea34.zip | |
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 <drosenberg@vsecurity.com>
Cc: stable@kernel.org
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
| -rw-r--r-- | fs/bio.c | 14 |
1 files changed, 13 insertions, 1 deletions
@@ -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) { |