Re: [PATCH 0/3] firewire: core: fix potential memory leak in build_tree()

[Takashi Sakamoto <o-takashi@sakamocchi.jp>]

On Tue, Aug 11, 2026 at 09:09:25PM +0900, Takashi Sakamoto wrote:
> Hi,
> 
> This patchset fixes a potential memory leak in the error path of
> build_tree(), reported by Abdun Nihaal[1].
> 
> The first two patches refactor build tree() to optimize port counting and
> the place of parent port validation. The last patch fixes the error path
> to release allocated node instances properly.
> 
> The changes were verified using the kmem:kmalloc and kmem:kfree
> tracepoints together with the KUnit tests added in my former patchset[2].
> The kmem:kfree events appear in the issued cases:
> 
> ```
> kmalloc: call_site=build_tree+0x228/0x620 ptr=ffffa10b013f0b00 bytes_req=64 bytes_alloc=64 gfp_flags=GFP_ATOMIC|__GFP_ZERO node=-1 accounted=false
> kmalloc: call_site=build_tree+0x228/0x620 ptr=ffffa10b013f0b40 bytes_req=48 bytes_alloc=64 gfp_flags=GFP_ATOMIC|__GFP_ZERO node=-1 accounted=false
> kmalloc: call_site=build_tree+0x228/0x620 ptr=ffffa10b013f0b80 bytes_req=64 bytes_alloc=64 gfp_flags=GFP_ATOMIC|__GFP_ZERO node=-1 accounted=false
> firewire_core node_tree_test_invalid_parent_port_count.dummy-device: parent port inconsistency for node 3: parent_count=2
> kfree: call_site=for_each_fw_node+0x17c/0x230 ptr=ffffa10b013f0b80
> kfree: call_site=for_each_fw_node+0x17c/0x230 ptr=ffffa10b013f0b00
> kfree: call_site=for_each_fw_node+0x17c/0x230 ptr=ffffa10b013f0b40
> ```
> 
> [1][PATCH v2] firewire: core: fix possible memory leak in build_tree()
> https://lore.kernel.org/lkml/20260801110915.82561-1-nihaal@cse.iitm.ac.in/
> [2][PATCH 0/3] firewire: core: add KUnit tests for tree building
> https://lore.kernel.org/lkml/20260810064119.410324-1-o-takashi@sakamocchi.jp/
> 
> 
> Takashi Sakamoto (3):
>   firewire: core: consolidate port counting in build_tree()
>   firewire: core: validate parent port count before allocating nodes in
>     build_tree()
>   firewire: core: fix memory leak in error path of build_tree()
> 
>  drivers/firewire/core-topology.c | 58 ++++++++++++++++++++------------
>  1 file changed, 36 insertions(+), 22 deletions(-)

Applied to for-next branch, with some removals of code comments in
node-tree-test.c addressing to the memory leak.


Regards

Takashi Sakamoto