linux-kernel - Re: [patch v2] x86, efi: fix pointer math issue in handle

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Date:	Mon, 05 Mar 2012 19:42:31 +0100
From:	walter harms <wharms@....de>
To:	Dan Carpenter <dan.carpenter@...cle.com>
CC:	"H. Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>, x86@...nel.org,
	Matt Fleming <matt.fleming@...el.com>,
	Maarten Lankhorst <m.b.lankhorst@...il.com>,
	linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [patch v2] x86, efi: fix pointer math issue in handle_ramdisks()



Am 05.03.2012 19:06, schrieb Dan Carpenter:
> "filename" is a efi_char16_t string so this check for reaching the end
> of the array doesn't work.  We need to cast the pointer to (u8 *) before
> doing the math.
> 
> This patch changes the "filename" to "filename_16" to avoid confusion in
> the future.
> 

maybe it is a bit late,  but ...
is efi_char16_t a generic requirement for EFI ? perhaps we can use wchar_t
since it is intended for such cases. additional we would get an api for free.

just my 2 cents,
 wh


> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> ---
> v2: Rename "filename" to "filename_16"
>     Also changed cast from (char *) to (u8 *) because it's not a C
>     character string.  Ingo suggested (void *) but that's a GCCism
>     I think.
> 
> diff --git a/arch/x86/boot/compressed/eboot.c b/arch/x86/boot/compressed/eboot.c
> index fec216f..0cdfc0d 100644
> --- a/arch/x86/boot/compressed/eboot.c
> +++ b/arch/x86/boot/compressed/eboot.c
> @@ -539,7 +539,7 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
>  		struct initrd *initrd;
>  		efi_file_handle_t *h;
>  		efi_file_info_t *info;
> -		efi_char16_t filename[256];
> +		efi_char16_t filename_16[256];
>  		unsigned long info_sz;
>  		efi_guid_t info_guid = EFI_FILE_INFO_ID;
>  		efi_char16_t *p;
> @@ -552,14 +552,14 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
>  		str += 7;
>  
>  		initrd = &initrds[i];
> -		p = filename;
> +		p = filename_16;
>  
>  		/* Skip any leading slashes */
>  		while (*str == '/' || *str == '\\')
>  			str++;
>  
>  		while (*str && *str != ' ' && *str != '\n') {
> -			if (p >= filename + sizeof(filename))
> +			if ((u8 *)p >= (u8 *)filename_16 + sizeof(filename_16))
>  				break;
>  
>  			*p++ = *str++;
> @@ -583,7 +583,7 @@ static efi_status_t handle_ramdisks(efi_loaded_image_t *image,
>  				goto free_initrds;
>  		}
>  
> -		status = efi_call_phys5(fh->open, fh, &h, filename,
> +		status = efi_call_phys5(fh->open, fh, &h, filename_16,
>  					EFI_FILE_MODE_READ, (u64)0);
>  		if (status != EFI_SUCCESS)
>  			goto close_handles;
> --
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> 
> 
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