CVE-2024-50273

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> btrfs: reinitialize delayed ref list after deleting it from the list<br /> <br /> At insert_delayed_ref() if we need to update the action of an existing<br /> ref to BTRFS_DROP_DELAYED_REF, we delete the ref from its ref head&amp;#39;s<br /> ref_add_list using list_del(), which leaves the ref&amp;#39;s add_list member<br /> not reinitialized, as list_del() sets the next and prev members of the<br /> list to LIST_POISON1 and LIST_POISON2, respectively.<br /> <br /> If later we end up calling drop_delayed_ref() against the ref, which can<br /> happen during merging or when destroying delayed refs due to a transaction<br /> abort, we can trigger a crash since at drop_delayed_ref() we call<br /> list_empty() against the ref&amp;#39;s add_list, which returns false since<br /> the list was not reinitialized after the list_del() and as a consequence<br /> we call list_del() again at drop_delayed_ref(). This results in an<br /> invalid list access since the next and prev members are set to poison<br /> pointers, resulting in a splat if CONFIG_LIST_HARDENED and<br /> CONFIG_DEBUG_LIST are set or invalid poison pointer dereferences<br /> otherwise.<br /> <br /> So fix this by deleting from the list with list_del_init() instead.