From: Matthew Wilcox (Oracle) <willy@infradead.org>
Date: Sat, 2 Nov 2019 04:25:08 +0000 (-0400)
Subject: idr: Fix idr_alloc_u32 on 32-bit systems
X-Git-Tag: Ubuntu-5.13.0-19.19~7370^2
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=b7e9728f3d7fc5c5c8508d99f1675212af5cfd49;p=mirror_ubuntu-jammy-kernel.git

idr: Fix idr_alloc_u32 on 32-bit systems

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>
---

diff --git a/lib/radix-tree.c b/lib/radix-tree.c
index 18c1dfbb1765..c8fa1d274530 100644
--- a/lib/radix-tree.c
+++ b/lib/radix-tree.c
@@ -1529,7 +1529,7 @@ void __rcu **idr_get_free(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;