linux-kernel - RE: [PATCH 2/5] efibc: Fix excessive stack footprint warning

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Date:	Mon, 9 May 2016 23:41:01 +0000
From:	"Elliott, Robert (Persistent Memory)" <elliott@....com>
To:	Matt Fleming <matt@...eblueprint.co.uk>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	"H . Peter Anvin" <hpa@...or.com>
CC:	Jeremy Compostella <jeremy.compostella@...el.com>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	Arnd Bergmann <arnd@...db.de>
Subject: RE: [PATCH 2/5] efibc: Fix excessive stack footprint warning

> -----Original Message-----
> From: linux-kernel-owner@...r.kernel.org [mailto:linux-kernel-
> owner@...r.kernel.org] On Behalf Of Matt Fleming
> Sent: Friday, May 06, 2016 4:39 PM
...
> Subject: [PATCH 2/5] efibc: Fix excessive stack footprint warning
> 
> From: Jeremy Compostella <jeremy.compostella@...el.com>
> 
...
> 
> -static void efibc_set_variable(const char *name, const char *value)
> +static int efibc_set_variable(const char *name, const char *value)
>  {
>  	int ret;
>  	efi_guid_t guid = LINUX_EFI_LOADER_ENTRY_GUID;
> -	struct efivar_entry entry;
> +	struct efivar_entry *entry;
>  	size_t size = (strlen(value) + 1) * sizeof(efi_char16_t);
> 
> -	if (size > sizeof(entry.var.Data))
> +	if (size > sizeof(entry->var.Data)) {
>  		pr_err("value is too large");

That pr_err is introduced by patch 25/40 of the first series.

How about including the name of the variable for which this is failing, 
like the final pr_err?

> +		return -EINVAL;
> +	}
> 
> -	efibc_str_to_str16(name, entry.var.VariableName);
> -	efibc_str_to_str16(value, (efi_char16_t *)entry.var.Data);
> -	memcpy(&entry.var.VendorGuid, &guid, sizeof(guid));
> +	entry = kmalloc(sizeof(*entry), GFP_KERNEL);
> +	if (!entry) {
> +		pr_err("failed to allocate efivar entry");

How about including the name of the variable for which this
is failing, like the final pr_err?

> +		return -ENOMEM;
> +	}
> 
> -	ret = efivar_entry_set(&entry,
> +	efibc_str_to_str16(name, entry->var.VariableName);
> +	efibc_str_to_str16(value, (efi_char16_t *)entry->var.Data);
> +	memcpy(&entry->var.VendorGuid, &guid, sizeof(guid));
> +
> +	ret = efivar_entry_set(entry,
>  			       EFI_VARIABLE_NON_VOLATILE
>  			       | EFI_VARIABLE_BOOTSERVICE_ACCESS
>  			       | EFI_VARIABLE_RUNTIME_ACCESS,
> -			       size, entry.var.Data, NULL);
> +			       size, entry->var.Data, NULL);
>  	if (ret)
>  		pr_err("failed to set %s EFI variable: 0x%x\n",
>  		       name, ret);
> +
> +	kfree(entry);
> +	return ret;
>  }