Commit bf77ae4c authored Jan 03, 2019 by NeilBrown Committed by Jeff Layton Jan 02, 2019

locks: fix error in locks_move_blocks()



After moving all requests from
   fl->fl_blocked_requests
to
   new->fl_blocked_requests

it is nonsensical to do anything to all the remaining elements, there
aren't any.  This should do something to all the requests that have been
moved. For simplicity, it does it to all requests in the target list.

Setting "f->fl_blocker = new" to all members of new->fl_blocked_requests
is "obviously correct" as it preserves the invariant of the linkage
among requests.

Reported-by:  <syzbot+239d99847eb49ecb3899@syzkaller.appspotmail.com>
Fixes: 5946c431 ("fs/locks: allow a lock request to block other requests.")
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Jeff Layton <jlayton@kernel.org>

parent 8e143b90

fs/locks.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -453,7 +453,7 @@ static void locks_move_blocks(struct file_lock new, struct file_lock fl)
		return;
		spin_lock(&blocked_lock_lock);
		list_splice_init(&fl->fl_blocked_requests, &new->fl_blocked_requests);
		list_for_each_entry(f, &fl->fl_blocked_requests, fl_blocked_member)
		list_for_each_entry(f, &new->fl_blocked_requests, fl_blocked_member)
		f->fl_blocker = new;
		spin_unlock(&blocked_lock_lock);
		}

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