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[v2,17/17] idr: Warn if old iterators see large IDs

Message ID 20171129201922.24370-18-willy@infradead.org
State Not Applicable, archived
Delegated to: David Miller
Headers show
Series IDR changes for v4.15-rc1 | expand

Commit Message

Matthew Wilcox (Oracle) Nov. 29, 2017, 8:19 p.m. UTC 
From: Matthew Wilcox <mawilcox@microsoft.com>

Now that the IDR can be used to store large IDs, it is possible somebody
might only partially convert their old code and use the iterators which
can only handle IDs up to INT_MAX.  It's probably unwise to show them a
truncated ID, so settle for spewing warnings to dmesg, and terminating
the iteration.

Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
---
 lib/idr.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/lib/idr.c b/lib/idr.c
index 772a24513d1e..1aaeb5a8c426 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -145,7 +145,11 @@  int idr_for_each(const struct idr *idr,
 	void __rcu **slot;
 
 	radix_tree_for_each_slot(slot, &idr->idr_rt, &iter, 0) {
-		int ret = fn(iter.index, rcu_dereference_raw(*slot), data);
+		int ret;
+
+		if (WARN_ON_ONCE(iter.index > INT_MAX))
+			break;
+		ret = fn(iter.index, rcu_dereference_raw(*slot), data);
 		if (ret)
 			return ret;
 	}
@@ -173,6 +177,9 @@  void *idr_get_next(struct idr *idr, int *nextid)
 	if (!slot)
 		return NULL;
 
+	if (WARN_ON_ONCE(iter.index > INT_MAX))
+		return NULL;
+
 	*nextid = iter.index;
 	return rcu_dereference_raw(*slot);
 }