Affected: Linux

In the Linux kernel, the following vulnerability has been resolved:

ocfs2: rebase copied fsdlm LVB pointers in locking_state

The locking_state debugfs iterator snapshots struct ocfs2_lock_res by value under ocfs2_dlm_tracking_lock and later formats that copy in ocfs2_dlm_seq_show(). That is fine for the inline fields, but the userspace fsdlm stack stores the LVB through lksb_fsdlm.sb_lvbptr. Once the iterator drops the tracking lock, a copied non-NULL sb_lvbptr still points into the original lockres owner, so teardown can free that container before the debugfs dump walks the raw LVB bytes.

Rebase the copied sb_lvbptr to the copied l_lksb before dumping the raw LVB. The seq snapshot already carries the inline LVB storage reserved in struct ocfs2_dlm_lksb, so the debugfs reader can dump the copied bytes without borrowing the original lockres lifetime.

The buggy scenario involves two paths, with each column showing the order within that path:

locking_state reader: lockres teardown: 1. ocfs2_dlm_seq_start()/next() 1. file release or another owner copies struct ocfs2_lock_res teardown reaches 2. ocfs2_dlm_seq_show() formats ocfs2_lock_res_free() the copied row 2. the lockres is removed from the 3. ocfs2_dlm_lvb() follows the tracking list copied sb_lvbptr 3. the owner frees the original lockres container

Validation reproduced th…