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 <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Jan Kara
2010-08-19 14:13:33 -07:00
committed by Linus Torvalds
parent f2e41e9103
commit d5ed3a4af7
2 changed files with 6 additions and 2 deletions

View File

@@ -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);