[PATCH 1/2] ocfs2: bound namelen in dlm_migrate_request_handler

From: Bryam Vargas <[email protected]>

A node receiving a DLM_MIGRATE_REQUEST message trusts the peer-supplied
name length (migrate->namelen) without bounding it.  dlm_init_mle() then
copies that many bytes into the fixed DLM_LOCKID_NAME_MAX-byte mname[]
array of an o2dlm_mle slab object, so a malformed message from a cluster
peer overflows the slab object by up to ~215 bytes: a heap out-of-bounds
write of attacker-controlled data, reachable by any node in the domain.

Reject an oversized name, the way dlm_master_request_handler() and the
other o2dlm receive handlers already do; the migration handler omits the
check entirely.  Conforming messages are unaffected.

Fixes: 6714d8e86bf4 ("[PATCH] OCFS2: The Second Oracle Cluster Filesystem")
Cc: [email protected]
Signed-off-by: Bryam Vargas <[email protected]>
---
 fs/ocfs2/dlm/dlmmaster.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/ocfs2/dlm/dlmmaster.c b/fs/ocfs2/dlm/dlmmaster.c
index 93eff38fdadd..bd7623cc6e77 100644
--- a/fs/ocfs2/dlm/dlmmaster.c
+++ b/fs/ocfs2/dlm/dlmmaster.c
@@ -3100,6 +3100,12 @@ int dlm_migrate_request_handler(struct o2net_msg *msg, u32 len, void *data,
 
 	name = migrate->name;
 	namelen = migrate->namelen;
+	if (namelen > DLM_LOCKID_NAME_MAX) {
+		mlog(ML_ERROR, "%s: invalid name length %u in migrate request\n",
+		     dlm->name, namelen);
+		ret = -EINVAL;
+		goto leave;
+	}
 	hash = dlm_lockid_hash(name, namelen);
 
 	/* preallocate.. if this fails, abort */

-- 
2.43.0