[dm-devel] Patch "dm btree: add a defensive bounds check to insert_at()" has been added to the 5.10-stable tree

[Sasha Levin]

This is a note to let you know that I've just added the patch titled

    dm btree: add a defensive bounds check to insert_at()

to the 5.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dm-btree-add-a-defensive-bounds-check-to-insert_at.patch
and it can be found in the queue-5.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable at vger.kernel.org> know about it.



commit 592c3f8827a2ca30bba60554dbeb891575e4f2e9
Author: Joe Thornber <ejt at redhat.com>
Date:   Fri Dec 10 13:44:13 2021 +0000

    dm btree: add a defensive bounds check to insert_at()
    
    [ Upstream commit 85bca3c05b6cca31625437eedf2060e846c4bbad ]
    
    Corrupt metadata could trigger an out of bounds write.
    
    Signed-off-by: Joe Thornber <ejt at redhat.com>
    Signed-off-by: Mike Snitzer <snitzer at redhat.com>
    Signed-off-by: Sasha Levin <sashal at kernel.org>

diff --git a/drivers/md/persistent-data/dm-btree.c b/drivers/md/persistent-data/dm-btree.c
index ef6e78d45d5b8..ee3e63aa864bf 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;