linux-kernel - Re: [PATCH] platform/x86/intel/tpmi/plr: Uninitialized variable in plr_print

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Message-ID: <1467f140-c035-cb2a-20d9-b5910971cb56@linux.intel.com>
Date: Mon, 15 Jul 2024 12:25:21 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Dan Carpenter <dan.carpenter@...aro.org>
cc: Tero Kristo <tero.kristo@...ux.intel.com>, 
    Hans de Goede <hdegoede@...hat.com>, 
    Andy Shevchenko <andriy.shevchenko@...ux.intel.com>, 
    platform-driver-x86@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>, 
    kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] platform/x86/intel/tpmi/plr: Uninitialized variable in
 plr_print_bits()

On Fri, 12 Jul 2024, Dan Carpenter wrote:

> Initialize the "str" pointer to NULL.  There is a test later for if "str"
> is NULL but in the original code it was either valid or uninitialized.
> 
> Fixes: 9e9397a41b7b ("platform/x86/intel/tpmi/plr: Add support for the plr mailbox")
> Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> ---
> Almost everyone automatically initializes stack variables to zero these days so
> bugs like this don't show up in testing and we disabled GCC's uninitialized
> variable warning so it's easy to miss.
> 
>  drivers/platform/x86/intel/intel_plr_tpmi.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/platform/x86/intel/intel_plr_tpmi.c b/drivers/platform/x86/intel/intel_plr_tpmi.c
> index c1aa52c23d25..2725a1ddba92 100644
> --- a/drivers/platform/x86/intel/intel_plr_tpmi.c
> +++ b/drivers/platform/x86/intel/intel_plr_tpmi.c
> @@ -162,7 +162,7 @@ static int plr_clear_cpu_status(struct tpmi_plr_die *plr_die, int cpu)
>  static void plr_print_bits(struct seq_file *s, u64 val, int bits)
>  {
>  	const unsigned long mask[] = { BITMAP_FROM_U64(val) };
> -	const char *str;
> +	const char *str = NULL;
>  	int bit, index;
>  
>  	for_each_set_bit(bit, mask, bits) {

This fix looks slightly incorrect. It silences warning but for logic 
correctness, the NULL assignment seems to belong inside the for loop so 
it's done for each bit.

-- 
 i.