[PATCH 5.4 215/320] dm btree: add a defensive bounds check to insert_at()

Greg Kroah-Hartman
2022-01-24T19:40:56Z

From: Joe Thornber <ejt@redhat.com>

[ Upstream commit 85bca3c05b6cca31625437eedf2060e846c4bbad ]

Corrupt metadata could trigger an out of bounds write.

Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/md/persistent-data/dm-btree.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index 8aae0624a2971..6383afb88f319 100644
--- a/drivers/md/persistent-data/dm-btree.c
+++ b/drivers/md/persistent-data/dm-btree.c
@@ -83,14 +83,16 @@ void inc_children(struct dm_transaction_manager *tm, struct btree_node *n,
}

static int insert_at(size_t value_size, struct btree_node *node, unsigned index,
- uint64_t key, void *value)
- __dm_written_to_disk(value)
+ uint64_t key, void *value)
+ __dm_written_to_disk(value)
{
uint32_t nr_entries = le32_to_cpu(node->header.nr_entries);
+ uint32_t max_entries = le32_to_cpu(node->header.max_entries);
__le64 key_le = cpu_to_le64(key);

if (index > nr_entries ||
- index >= le32_to_cpu(node->header.max_entries)) {
+ index >= max_entries ||
+ nr_entries >= max_entries) {
DMERR("too many entries in btree node for insert");
__dm_unbless_for_disk(value);
return -ENOMEM;
--
2.34.1