lua-lsm: put looked-up task after descendant walk#15
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* lua-lsm: validate inode_init_security xattr output * lua-lsm: own inode_init_security xattr name storage * lua-lsm: document OCFS2 xattr name lifetime issue --------- Signed-off-by: Zongyao Chen <ZongYao.Chen@linux.alibaba.com>
kernel_task_is_descendant() accepts either a task userdata or a pid. The pid path takes a task reference with find_get_task_by_vpid(), but the RCU walk may replace parent with parent->group_leader before the final put_task_struct(). When the pid names a non-leader thread, this leaks the looked-up task and drops a reference from the group leader without having acquired one here. Keep the looked-up task in a separate pointer and release that reference after the walk. The group leader pointer is only used for comparison under the RCU read-side critical section. Signed-off-by: Zongyao Chen <ZongYao.Chen@linux.alibaba.com>
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kernel_task_is_descendant() accepts either a task userdata or a pid. The pid path takes a task reference with find_get_task_by_vpid(), but the RCU walk may replace parent with parent->group_leader before the final put_task_struct().
When the pid names a non-leader thread, this leaks the looked-up task and drops a reference from the group leader without having acquired one here.
Keep the looked-up task in a separate pointer and release that reference after the walk. The group leader pointer is only used for comparison under the RCU read-side critical section.
Validation:
Signed-off-by: Zongyao Chen ZongYao.Chen@linux.alibaba.com