Re: [PATCH] net: add missing ref_tracker_dir_exit() to alloc_netdev_mqs()

On Sat, Aug 15, 2026 at 8:50 AM Tetsuo Handa
<[email protected]> wrote:
>
> sashiko is reporting that trying to read /sys/kernel/debug/ref_tracker/*
> causes use-afer-free crash when either alloc_percpu() or dev_addr_init()
> in alloc_netdev_mqs() failed, for commit 4d92b95ff2f9 ("net: add net device
> refcount tracker infrastructure") added ref_tracker_dir_exit() to only
> free_netdev() path.
>
> Reported-by: sashiko.dev (no mail address)
> Closes: https://sashiko.dev/#/patchset/56c707e7-1fb0-43ec-b8fb-cf6f451e513e%40I-love.SAKURA.ne.jp
> Fixes: 4d92b95ff2f9 ("net: add net device refcount tracker infrastructure")
> Signed-off-by: Tetsuo Handa <[email protected]>

I have the same remark.

Fixes: 4d92b95ff2f9 ("net: add net device refcount tracker
infrastructure") is where the omission originated in Linux 5.18,
though it was benign until debugfs registration was added to ref_tracker.

Reviewed-by: Eric Dumazet <[email protected]>