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| author | Jens Axboe <jaxboe@fusionio.com> | 2010-11-10 14:36:25 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-12-09 13:24:17 -0800 |
| commit | 99b6f6c69d47e4e61856884e96020bb4a57d6158 (patch) | |
| tree | 983bfa2377657a6295b52ffb3cf727fd5ac5789a | |
| parent | b2fcddfdd588f3a719fc50f3ef0934daa0d2cbe1 (diff) | |
| download | lwn-99b6f6c69d47e4e61856884e96020bb4a57d6158.tar.gz lwn-99b6f6c69d47e4e61856884e96020bb4a57d6158.zip | |
bio: take care not overflow page count when mapping/copying user data
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>
| -rw-r--r-- | fs/bio.c | 14 |
1 files changed, 13 insertions, 1 deletions
@@ -593,6 +593,12 @@ struct bio *bio_copy_user_iov(struct request_queue *q, struct sg_iovec *iov, 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; } @@ -691,6 +697,12 @@ 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 @@ -718,7 +730,7 @@ 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) { |