linux-kernel - Re: [PATCH 10/17] delta: Fix buffer overrun in delta_ipc

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Message-ID: <bb7d9aeb-9cde-92c6-cbd1-c0ba3d283f07@st.com>
Date:   Mon, 1 Apr 2019 13:37:56 +0000
From:   Hugues FRUCHET <hugues.fruchet@...com>
To:     Andi Kleen <andi@...stfloor.org>, "x86@...nel.org" <x86@...nel.org>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        "mchehab@...pensource.com" <mchehab@...pensource.com>
Subject: Re: [PATCH 10/17] delta: Fix buffer overrun in delta_ipc_open

Hi Andi,

We have already discussed about that here:
https://lore.kernel.org/patchwork/patch/866406/

Now that strscpy is largely deployed within kernel, could you retest 
with the change I suggested ?

Best regards,
Hugues.

On 3/21/19 11:00 PM, Andi Kleen wrote:
> From: Andi Kleen <ak@...ux.intel.com>
> 
> delta_ipc_open is always called with a single constant string
> as name, but it uses a longer memcpy to copy the string to
> a different structure. The memcpy would read outside the bounds
> of the string, potentially accessing unmapped memory.
> 
> Just use strcpy instead after clearing the area.
> 
> This fixes a build error with LTO, which can detect this.
> 
> Cc: hugues.fruchet@...com
> Cc: mchehab@...pensource.com
> Fixes: 91c83f395fbe [media] st-delta: rpmsg ipc support
> Signed-off-by: Andi Kleen <ak@...ux.intel.com>
> ---
>   drivers/media/platform/sti/delta/delta-ipc.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/platform/sti/delta/delta-ipc.c b/drivers/media/platform/sti/delta/delta-ipc.c
> index a4603d573c34..bd1bbbeedec3 100644
> --- a/drivers/media/platform/sti/delta/delta-ipc.c
> +++ b/drivers/media/platform/sti/delta/delta-ipc.c
> @@ -175,8 +175,8 @@ int delta_ipc_open(struct delta_ctx *pctx, const char *name,
>   	msg.ipc_buf_size = ipc_buf_size;
>   	msg.ipc_buf_paddr = ctx->ipc_buf->paddr;
>   
> -	memcpy(msg.name, name, sizeof(msg.name));
> -	msg.name[sizeof(msg.name) - 1] = 0;
> +	memset(msg.name, 0, sizeof(msg.name));
> +	strcpy(msg.name, name);
>   
>   	msg.param_size = param->size;
>   	memcpy(ctx->ipc_buf->vaddr, param->data, msg.param_size);
>