[PATCH 4.14 010/209] idr: Fix idr_alloc_u32 on 32-bit systems

Greg Kroah-Hartman
2019-12-04T18:01:17Z

From: Matthew Wilcox (Oracle) <willy@infradead.org>

[ Upstream commit b7e9728f3d7fc5c5c8508d99f1675212af5cfd49 ]

Attempting to allocate an entry at 0xffffffff when one is already
present would succeed in allocating one at 2^32, which would confuse
everything. Return -ENOSPC in this case, as expected.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
lib/radix-tree.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index d172f0341b807..ff00c816266b1 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -2184,7 +2184,7 @@ void __rcu **idr_get_free_cmn(struct radix_tree_root *root,
offset = radix_tree_find_next_bit(node, IDR_FREE,
offset + 1);
start = next_index(start, node, offset);
- if (start > max)
+ if (start > max || start == 0)
return ERR_PTR(-ENOSPC);
while (offset == RADIX_TREE_MAP_SIZE) {
offset = node->offset + 1;
--
2.20.1