CVE-2026-31577

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> nilfs2: fix NULL i_assoc_inode dereference in nilfs_mdt_save_to_shadow_map<br /> <br /> The DAT inode&amp;#39;s btree node cache (i_assoc_inode) is initialized lazily<br /> during btree operations. However, nilfs_mdt_save_to_shadow_map()<br /> assumes i_assoc_inode is already initialized when copying dirty pages<br /> to the shadow map during GC.<br /> <br /> If NILFS_IOCTL_CLEAN_SEGMENTS is called immediately after mount before<br /> any btree operation has occurred on the DAT inode, i_assoc_inode is<br /> NULL leading to a general protection fault.<br /> <br /> Fix this by calling nilfs_attach_btree_node_cache() on the DAT inode<br /> in nilfs_dat_read() at mount time, ensuring i_assoc_inode is always<br /> initialized before any GC operation can use it.