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>
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@@ -836,7 +836,8 @@ void tag_pages_for_writeback(struct address_space *mapping,
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spin_unlock_irq(&mapping->tree_lock);
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WARN_ON_ONCE(tagged > WRITEBACK_TAG_BATCH);
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cond_resched();
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} while (tagged >= WRITEBACK_TAG_BATCH);
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/* We check 'start' to handle wrapping when end == ~0UL */
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} while (tagged >= WRITEBACK_TAG_BATCH && start);
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}
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EXPORT_SYMBOL(tag_pages_for_writeback);
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