Re: [PATCH] wmi: Fix kernel panic when stack protection enabled.

From: Carlos Corbacho <carlos@strangeworlds.co.uk>
To: "lcostantino@gmail.com" <lcostantino@gmail.com>
Cc: linux-acpi@vger.kernel.org, Len Brown <lenb@kernel.org>
Subject: Re: [PATCH] wmi: Fix kernel panic when stack protection enabled.
Date: Tue, 9 Jun 2009 20:46:24 +0100	[thread overview]
Message-ID: <200906092046.24983.carlos@strangeworlds.co.uk> (raw)
In-Reply-To: <alpine.DEB.2.00.0906091707380.8360@debian>

[Adding Len to CC]

On Tuesday 09 Jun 2009 22:09:23 lcostantino@gmail.com wrote:
> From: Costantino Leandro <lcostantino@gmail.com>
>
> Summary:
> Kernel panic arise when stack protection is enabled, since strncat will
> add a null terminating byte '\0'; So in functions
> like this one (wmi_query_block):
>         char wc[4]="WC";
> 	....
> 	strncat(method, block->object_id, 2);
>         ...
> the length of wc should be n+1 (wc[5]) or stack protection
> fault will arise. This is not noticeable when stack protection is
> disabled,but , isn't good either.
> Config used: [CONFIG_CC_STACKPROTECTOR_ALL=y,
> 	      CONFIG_CC_STACKPROTECTOR=y]
>
> Panic Trace
> ------------
>        .... stack-protector: kernel stack corrupted in : fa7b182c
>        2.6.30-rc8-obelisco-generic
>        call_trace:
>            [<c04a6c40>] ? panic+0x45/0xd9
> 	   [<c012925d>] ? __stack_chk_fail+0x1c/0x40
> 	   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
> 	   [<fa7b182c>] ? wmi_query_block+0x15a/0x162 [wmi]
> 	   [<fa7e7000>] ? acer_wmi_init+0x00/0x61a [acer_wmi]
> 	   [<fa7e7135>] ? acer_wmi_init+0x135/0x61a [acer_wmi]
> 	   [<c0101159>] ? do_one_initcall+0x50+0x126
>
> Signed-off-by: Costantino Leandro <lcostantino@gmail.com>

Acked-by: Carlos Corbacho <carlos@strangeworlds.co.uk>

Len, can you take this one for 2.6.31?

> ---
>  drivers/platform/x86/wmi.c |    8 ++++----
>  1 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/platform/x86/wmi.c b/drivers/platform/x86/wmi.c
> index 043b208..f215a59 100644
> --- a/drivers/platform/x86/wmi.c
> +++ b/drivers/platform/x86/wmi.c
> @@ -270,7 +270,7 @@ u32 method_id, const struct acpi_buffer *in, struct
> acpi_buffer *out) acpi_status status;
>  	struct acpi_object_list input;
>  	union acpi_object params[3];
> -	char method[4] = "WM";
> +	char method[5] = "WM";
>
>  	if (!find_guid(guid_string, &wblock))
>  		return AE_ERROR;
> @@ -328,8 +328,8 @@ struct acpi_buffer *out)
>  	acpi_status status, wc_status = AE_ERROR;
>  	struct acpi_object_list input, wc_input;
>  	union acpi_object wc_params[1], wq_params[1];
> -	char method[4];
> -	char wc_method[4] = "WC";
> +	char method[5];
> +	char wc_method[5] = "WC";
>
>  	if (!guid_string || !out)
>  		return AE_BAD_PARAMETER;
> @@ -410,7 +410,7 @@ const struct acpi_buffer *in)
>  	acpi_handle handle;
>  	struct acpi_object_list input;
>  	union acpi_object params[2];
> -	char method[4] = "WS";
> +	char method[5] = "WS";
>
>  	if (!guid_string || !in)
>  		return AE_BAD_DATA;

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