Re: [PATCH 1/2] firewire: Kill unnecessary buf check in device_attribute.show

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

Hi,

On Mon, Mar 18, 2024 at 06:24:52AM +0000, Zhijian Li (Fujitsu) wrote:
> ...
> Sorry for the mistake. I haven't considered callers from other than sysfs.
> I'm fine to reverting both *two*.
> 
> If we are interesting in the sysfs_emit conversion one, i cooked(see the attachment)
> a patch to revert "firewire: Kill unnecessary buf check in device_attribute.show" only.
> 
> (Feel free to ignore it if you have had a local fix.)
> ...
> From 96ad3e15b86e2504f3c17fd6a10be48e5ff81cb1 Mon Sep 17 00:00:00 2001
> From: Li Zhijian <lizhijian@fujitsu.com>
> Date: Mon, 18 Mar 2024 14:05:32 +0800
> Subject: [PATCH] Revert "firewire: Kill unnecessary buf check in
>  device_attribute.show"
> 
> This reverts commit 4a2b06ca33763b363038d333274e212db6ff0de1.
> 
> The previous fix didn't consider callers from other than sysfs. Revert
> it to fix the NULL dereference
> 
>  kernel:  ? sysfs_emit+0xb5/0xc0
>  kernel:  show_immediate+0x13f/0x1d0 [firewire_core]
>  kernel:  init_fw_attribute_group+0x81/0x150 [firewire_core]
>  kernel:  create_units+0x119/0x160 [firewire_core]
>  kernel:  fw_device_init+0x1a9/0x330 [firewire_core]
>  kernel:  fw_device_workfn+0x12/0x20 [firewire_core]
>  kernel:  process_one_work+0x16f/0x350
>  kernel:  worker_thread+0x306/0x440
>  kernel:  ? __pfx_worker_thread+0x10/0x10
>  kernel:  kthread+0xf2/0x120
>  kernel:  ? __pfx_kthread+0x10/0x10
>  kernel:  ret_from_fork+0x47/0x70
>  kernel:  ? __pfx_kthread+0x10/0x10
>  kernel:  ret_from_fork_asm+0x1b/0x30
>  kernel:  </TASK>
>  kernel: ---[ end trace 0000000000000000 ]---
>  kernel: ------------[ cut here ]------------
> 
> Fixes: 4a2b06ca3376 ("firewire: Kill unnecessary buf check in device_attribute.show")
> Reported-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
> Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
> ---
>  drivers/firewire/core-device.c | 16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)

Thanks for your immediate action. I applied it to for-linus branch, and
will send it in this week with my additional patch for notes. Let's back
to test, hehe.


Thanks

Takashi Sakamoto