From d5ed3a4af77b851b6271ad3d9abc4c57fa3ce0f5 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Thu, 19 Aug 2010 14:13:33 -0700 Subject: lib/radix-tree.c: fix overflow in radix_tree_range_tag_if_tagged() When radix_tree_maxindex() is ~0UL, it can happen that scanning overflows index and tree traversal code goes astray reading memory until it hits unreadable memory. Check for overflow and exit in that case. Signed-off-by: Jan Kara Cc: Christoph Hellwig Cc: Nick Piggin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page-writeback.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 7262aacea8a2..c09ef5219cbe 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -836,7 +836,8 @@ void tag_pages_for_writeback(struct address_space *mapping, spin_unlock_irq(&mapping->tree_lock); WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH); cond_resched(); - } while (tagged >= WRITEBACK_TAG_BATCH); + /* We check 'start' to handle wrapping when end == ~0UL */ + } while (tagged >= WRITEBACK_TAG_BATCH && start); } EXPORT_SYMBOL(tag_pages_for_writeback); -- cgit v1.2.3