diff --git a/fs/smb/server/smbacl.c b/fs/smb/server/smbacl.c
index fc9937cedb01..9c59c8f73b66 100644
--- a/fs/smb/server/smbacl.c
+++ b/fs/smb/server/smbacl.c
@@ -745,12 +745,18 @@ static void set_ntacl_dacl(struct mnt_idmap *idmap,
 			if (nt_ace_size > aces_size)
 				break;
 
+			if (ntace->sid.num_subauth == 0 ||
+			    ntace->sid.num_subauth > SID_MAX_SUB_AUTHORITIES)
+				goto next_ace;
+
 			memcpy((char *)pndace + size, ntace, nt_ace_size);
 			if (check_add_overflow(size, nt_ace_size, &size))
 				break;
+			num_aces++;
+
+next_ace:
 			aces_size -= nt_ace_size;
 			ntace = (struct smb_ace *)((char *)ntace + nt_ace_size);
-			num_aces++;
 		}
 	}