linux-kernel - Re: [PATCH v2] misc: fastrpc: fix potential fastrpc_invoke

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Date:   Tue, 12 May 2020 10:29:17 -0700
From:   Bjorn Andersson <bjorn.andersson@...aro.org>
To:     Srinivas Kandagatla <srinivas.kandagatla@...aro.org>
Cc:     gregkh@...uxfoundation.org, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, arnd@...db.de,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH v2] misc: fastrpc: fix potential fastrpc_invoke_ctx leak

On Tue 12 May 04:09 PDT 2020, Srinivas Kandagatla wrote:

> fastrpc_invoke_ctx can have refcount of 2 in error path where
> rpmsg_send() fails to send invoke message. decrement the refcount
> properly in the error path to fix this leak.
> 
> This also fixes below static checker warning:
> 
> drivers/misc/fastrpc.c:990 fastrpc_internal_invoke()
> warn: 'ctx->refcount.refcount.ref.counter' not decremented on lines: 990.
> 
> Fixes: c68cfb718c8f ("misc: fastrpc: Add support for context")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@...aro.org>

Thanks, that looks better.

Reviewed-by: Bjorn Andersson <bjorn.andersson@...aro.org>

Regards,
Bjorn

> ---
> Changes since v1:
> 	moved fastrpc_context_put to fastrpc_invoke_send()
> 
>  drivers/misc/fastrpc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 9065d3e71ff7..7939c55daceb 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -904,6 +904,7 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>  	struct fastrpc_channel_ctx *cctx;
>  	struct fastrpc_user *fl = ctx->fl;
>  	struct fastrpc_msg *msg = &ctx->msg;
> +	int ret;
>  
>  	cctx = fl->cctx;
>  	msg->pid = fl->tgid;
> @@ -919,7 +920,13 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>  	msg->size = roundup(ctx->msg_sz, PAGE_SIZE);
>  	fastrpc_context_get(ctx);
>  
> -	return rpmsg_send(cctx->rpdev->ept, (void *)msg, sizeof(*msg));
> +	ret = rpmsg_send(cctx->rpdev->ept, (void *)msg, sizeof(*msg));
> +
> +	if (ret)
> +		fastrpc_context_put(ctx);
> +
> +	return ret;
> +
>  }
>  
>  static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
> -- 
> 2.21.0
>