fix braino in generic_file_read_iter() (5b47d59a) · Commits · 戴 / test

Wrong sign of iov_iter_revert() argument. Unfortunately, slipped through the testing, since most of the time we don't do anything to the iterator afterwards and potential oops on walking the iter->iov too far backwards is too infrequent to be easily triggered. Add a sanity check in iov_iter_revert() to catch bugs like this one; fortunately, the same braino hadn't happened in other callers, but we'd better have a warning if such thing crops up. Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

lib/iov_iter.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -790,6 +790,8 @@ void iov_iter_revert(struct iov_iter *i, size_t unroll)
		{
		if (!unroll)
		return;
		if (WARN_ON(unroll > MAX_RW_COUNT))
		return;
		i->count += unroll;
		if (unlikely(i->type & ITER_PIPE)) {
		struct pipe_inode_info *pipe = i->pipe;

mm/filemap.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -2048,7 +2048,7 @@ generic_file_read_iter(struct kiocb iocb, struct iov_iter iter)
		iocb->ki_pos += retval;
		count -= retval;
		}
		iov_iter_revert(iter, iov_iter_count(iter) - count);
		iov_iter_revert(iter, count - iov_iter_count(iter));

		/*
		* Btrfs can have a short DIO read if we encounter

Admin message