iov_iter: Fix iov_iter_extract_pages() with zero-sized entries

iov_iter_extract_pages() doesn't correctly handle skipping over initial
zero-length entries in ITER_KVEC and ITER_BVEC-type iterators.

The problem is that it accidentally reduces maxsize to 0 when it
skipping and thus runs to the end of the array and returns 0.

Fix this by sticking the calculated size-to-copy in a new variable
rather than back in maxsize.

Fixes: 7d58fe731028 ("iov_iter: Add a function to extract a page list from an iterator")
Signed-off-by: David Howells <>
Reviewed-by: Christoph Hellwig <>
Cc: Christian Brauner <>
Cc: Jens Axboe <>
Cc: Al Viro <>
Cc: David Hildenbrand <>
Cc: John Hubbard <>
Signed-off-by: Linus Torvalds <>
1 file changed