linux-kernel - Re: [PATCH] thunderbolt_tb: add check for return value of 'tb_switch_find

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Date:   Fri, 17 Feb 2023 15:41:56 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Natalia Petrova <n.petrova@...tech.ru>
Cc:     Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        lvc-project@...uxtesting.org
Subject: Re: [PATCH] thunderbolt_tb: add check for return value of
 'tb_switch_find_port'

Hi,

On Fri, Feb 17, 2023 at 04:24:32PM +0300, Natalia Petrova wrote:
> Return value of 'tb_switch_find_port' has to be checked to avoid
> null pointer dereferences in functions tb_tunnel_alloc_dma() and

NULL

> tb_port_info().
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Fixes: 386e5e29d81c ("thunderbolt: Make tb_find_port() available to other files")
> Signed-off-by: Natalia Petrova <n.petrova@...tech.ru>
> ---
>  drivers/thunderbolt/tb.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
> index 9853f6c7e81d..5d6cded68d46 100644
> --- a/drivers/thunderbolt/tb.c
> +++ b/drivers/thunderbolt/tb.c
> @@ -1156,6 +1156,8 @@ static int tb_approve_xdomain_paths(struct tb *tb, struct tb_xdomain *xd,
>  	sw = tb_to_switch(xd->dev.parent);
>  	dst_port = tb_port_at(xd->route, sw);
>  	nhi_port = tb_switch_find_port(tb->root_switch, TB_TYPE_NHI);
> +	if (!nhi_port)

This really cannot happen in real life. All host routers must have a
host interface adapter so I'm not sure if adding these checks do
anything else than adding dead code.

> +		return -EIO;
>  
>  	mutex_lock(&tb->lock);
>  	tunnel = tb_tunnel_alloc_dma(tb, nhi_port, dst_port, transmit_path,
> -- 
> 2.34.1