On Mon, Feb 10, 2025 at 09:31:28AM -0500, Liam R. Howlett wrote: >* Wei Yang <richard.weiyang@xxxxxxxxx> [250207 20:26]: > >The subject of this patch set makes the issue sound much more sever than >it is. It currently sounds like a memory leak or a UAF, which isn't the >case. > Not intend to exaggerate the impact. Is this one would be better? maple_tree: make sure each node is dead on destroy >The root node may remain usable for the duration of the rcu window if >it's a leaf node. The impact is pretty minor - you may see the old data >on calls that happen in the same rcu window - which is the case anyways. > >You should also say maple_tree: in the subject since this is >going to linux-mm. Not a really big deal since each patch in the series >specifies the maple tree. > Thanks, will add it in next version. >> Per my understanding, on destroy we should set each node dead. But current >> code miss this when the maple tree has only the root node. >> >> The reason is mt_destroy_walk() leverage mte_destroy_descend() to set >> node dead, but this is skipped since the only root node is a leaf. >> >> Patch 1 fixes this. >> >> When adding a test case, I found we always get the new value even we leave the >> old root node not dead. It turns out we always re-walk the tree in mas_walk(). >> It looks like a typo on the status check of mas_walk(). >> >> Patch 2 fixes this. >> >> Patch 3 add a test case to assert retrieving new value when overwriting the >> whole range to a tree with only root node >> >> Wei Yang (3): >> maple_tree: may miss to set node dead on destroy >> maple_tree: restart walk on correct status >> maple_tree: assert retrieving new value on a tree with only root node >> >> lib/maple_tree.c | 4 +++- >> tools/testing/radix-tree/maple.c | 24 ++++++++++++++++++++++++ >> 2 files changed, 27 insertions(+), 1 deletion(-) >> >> -- >> 2.34.1 >> -- Wei Yang Help you, Help me
