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bio: take care not overflow page count when mapping/copying user data

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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>
This commit is contained in:
Jens Axboe 2010-11-10 14:36:25 +01:00
parent f3f63c1c28
commit cb4644cac4
1 changed files with 13 additions and 1 deletions
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14
fs/bio.c
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@ -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) {