linux-kernel - Re: [PATCH 1/3] gpio: Fix a potential abuse of seq

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Message-ID: <238c054f.ad0a.1934960d5fe.Coremail.00107082@163.com>
Date: Wed, 20 Nov 2024 19:41:43 +0800 (CST)
From: "David Wang" <00107082@....com>
To: "Geert Uytterhoeven" <geert@...ux-m68k.org>
Cc: linus.walleij@...aro.org, brgl@...ev.pl, kees@...nel.org, 
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] gpio: Fix a potential abuse of seq_printf() format
 string


At 2024-11-20 19:04:39, "Geert Uytterhoeven" <geert@...ux-m68k.org> wrote:
>Hi David,
>
>On Wed, Nov 20, 2024 at 10:15 AM David Wang <00107082@....com> wrote:
>> Using device name as format string of seq_printf() is prone to
>> "Format string attack", opens possibility for exploitation.
>> Seq_puts() is safer and more efficient.
>>
>> Signed-off-by: David Wang <00107082@....com>
>
>Thanks for your patch!
>
>> --- a/drivers/gpio/gpio-aspeed-sgpio.c
>> +++ b/drivers/gpio/gpio-aspeed-sgpio.c
>> @@ -420,7 +420,7 @@ static void aspeed_sgpio_irq_print_chip(struct irq_data *d, struct seq_file *p)
>>         int offset;
>>
>>         irqd_to_aspeed_sgpio_data(d, &gpio, &bank, &bit, &offset);
>> -       seq_printf(p, dev_name(gpio->dev));
>> +       seq_puts(p, dev_name(gpio->dev));
>
>If we want to add the missing space here, the code has to be changed
>to use seq_printf(..., " %s", ...) again.

It's kind of strange to add leading alignment spaces in a function named xxx_print_chip(); 

>
>However, it might be simpler to move this to the core. I.e. add an
>unconditional seq_putc(p, ' ') to show_interrupts()[1], and drop the
>spaces from all callbacks and from the fallbacks in show_interrupts().

I would vote for this approach,   if we want to fix  those misbehaving alignments.
It's cleaner.


>
>[1] https://elixir.bootlin.com/linux/v6.12/source/kernel/irq/proc.c#L503
>
>Gr{oetje,eeting}s,
>
>                        Geert
>
>-- 
>Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org
>
>In personal conversations with technical people, I call myself a hacker. But
>when I'm talking to journalists I just say "programmer" or something like that.
>                                -- Linus Torvalds


Thanks~
David