CVE-2024-49983

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

ext4: drop ppath from ext4_ext_replay_update_ex() to avoid double-free

When calling ext4_force_split_extent_at() in ext4_ext_replay_update_ex(),

the 'ppath' is updated but it is the 'path' that is freed, thus potentially

triggering a double-free in the following process:

ext4_ext_replay_update_ex

ppath = path

ext4_force_split_extent_at(&ppath)

ext4_split_extent_at

ext4_ext_insert_extent

ext4_ext_create_new_leaf

ext4_ext_grow_indepth

ext4_find_extent

if (depth > path[0].p_maxdepth)

kfree(path) ---> path First freed

*orig_path = path = NULL ---> null ppath

kfree(path) ---> path double-free !!!

So drop the unnecessary ppath and use path directly to avoid this problem.

And use ext4_find_extent() directly to update path, avoiding unnecessary

memory allocation and freeing. Also, propagate the error returned by

ext4_find_extent() instead of using strange error codes.