On Wed, Jul 10, 2024 at 12:06:34PM +0800, libaokun@xxxxxxxxxxxxxxx wrote: > From: Baokun Li <libaokun1@xxxxxxxxxx> > > Hi all! > > This patch series is a hardening of ext4 extents path related code. > The following is a brief overview of the patches, see the patches for > more details. > > Patch 1-2: Refactor ext4_ext_rm_idx() as suggested by Jan, and add > appropriate error handling branches to ext4_ext_rm_idx() and > ext4_ext_correct_indexes() to avoid inconsistent extents tree. > PS: This comes from the previous work of my colleague zhanchengbin > (see link), who is no longer in charge of these and I have taken over. > Link: https://lore.kernel.org/r/20230213080514.535568-3-zhanchengbin1@xxxxxxxxxx/ > > Patch 3-4: Fix an issue that caused p_bh to be released twice if it wasn't > set to NULL after path->p_bh was released. And add a helper function after > the quick fix to prevent this from happening again. > > Patch 5-7: Quick fixes for use-after-free and double-free problems caused > by mixing path(pointer to an extent path) and ppath(pointer to an extent > path pointer). > > Patch 8-19: Now the use of path and ppath is so confusing that we can > trigger use-after-free or double-free by accessing a stale pointer, or > we can get a memory leak by forgetting to update ppath. And it's very > difficult to read the code. So to make the code more readable, get rid > of ppath and pass path between functions uniformly to avoid these risks. > > Patch 20: Reduces the consumption of unnecessary memory operations by > avoiding repetitive allocation and release paths. > > "kvm-xfstests -c ext4/all -g auto" has been executed with no new failures. > > Comments and questions are, as always, welcome. > Please let me know what you think. > > Thanks, > Baokun > > Baokun Li (20): > ext4: refactor ext4_ext_rm_idx() to index 'path' > ext4: prevent partial update of the extents path > ext4: fix double brelse() the buffer of the extents path > ext4: add new ext4_ext_path_brelse() helper > ext4: fix slab-use-after-free in ext4_split_extent_at() > ext4: avoid use-after-free in ext4_ext_show_leaf() > ext4: drop ppath from ext4_ext_replay_update_ex() to avoid double-free > ext4: get rid of ppath in ext4_find_extent() > ext4: get rid of ppath in get_ext_path() > ext4: get rid of ppath in ext4_ext_create_new_leaf() > ext4: get rid of ppath in ext4_ext_insert_extent() > ext4: get rid of ppath in ext4_split_extent_at() > ext4: get rid of ppath in ext4_force_split_extent_at() > ext4: get rid of ppath in ext4_split_extent() > ext4: get rid of ppath in ext4_split_convert_extents() > ext4: get rid of ppath in ext4_convert_unwritten_extents_endio() > ext4: get rid of ppath in ext4_ext_convert_to_initialized() > ext4: get rid of ppath in ext4_ext_handle_unwritten_extents() > ext4: get rid of ppath in convert_initialized_extent() > ext4: avoid unnecessary extent path frees and allocations > > fs/ext4/ext4.h | 9 +- > fs/ext4/extents.c | 746 +++++++++++++++++++++++------------------- > fs/ext4/fast_commit.c | 17 +- > fs/ext4/migrate.c | 5 +- > fs/ext4/move_extent.c | 36 +- > 5 files changed, 439 insertions(+), 374 deletions(-) > > -- > 2.39.2 Tested kvm-xfstests auto on Powerpc with 4k, 64k and adv and no new regressions are seen. Feel free to add: Tested-by: Ojaswin Mujoo <ojaswin@xxxxxxxxxxxxx> Regards, Ojaswin
