netdev - Re: [PATCH net v2] enic: Validate length of nl attributes in enic_set_vf

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Date: Thu, 27 Jun 2024 16:20:38 -0700
From: Stephen Hemminger <stephen@...workplumber.org>
To: Roded Zats <rzats@...oaltonetworks.com>
Cc: benve@...co.com, satishkh@...co.com, davem@...emloft.net,
 edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
 orcohen@...oaltonetworks.com, netdev@...r.kernel.org
Subject: Re: [PATCH net v2] enic: Validate length of nl attributes in
 enic_set_vf_port

On Wed, 22 May 2024 10:30:44 +0300
Roded Zats <rzats@...oaltonetworks.com> wrote:

> enic_set_vf_port assumes that the nl attribute IFLA_PORT_PROFILE
> is of length PORT_PROFILE_MAX and that the nl attributes
> IFLA_PORT_INSTANCE_UUID, IFLA_PORT_HOST_UUID are of length PORT_UUID_MAX.
> These attributes are validated (in the function do_setlink in rtnetlink.c)
> using the nla_policy ifla_port_policy. The policy defines IFLA_PORT_PROFILE
> as NLA_STRING, IFLA_PORT_INSTANCE_UUID as NLA_BINARY and
> IFLA_PORT_HOST_UUID as NLA_STRING. That means that the length validation
> using the policy is for the max size of the attributes and not on exact
> size so the length of these attributes might be less than the sizes that
> enic_set_vf_port expects. This might cause an out of bands
> read access in the memcpys of the data of these
> attributes in enic_set_vf_port.
> 
> Fixes: f8bd909183ac ("net: Add ndo_{set|get}_vf_port support for enic dynamic vnics")
> Signed-off-by: Roded Zats <rzats@...oaltonetworks.com>
> ---
>  drivers/net/ethernet/cisco/enic/enic_main.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/net/ethernet/cisco/enic/enic_main.c b/drivers/net/ethernet/cisco/enic/enic_main.c
> index f604119efc80..5f26fc3ad655 100644
> --- a/drivers/net/ethernet/cisco/enic/enic_main.c
> +++ b/drivers/net/ethernet/cisco/enic/enic_main.c
> @@ -1117,18 +1117,30 @@ static int enic_set_vf_port(struct net_device *netdev, int vf,
>  	pp->request = nla_get_u8(port[IFLA_PORT_REQUEST]);
>  
>  	if (port[IFLA_PORT_PROFILE]) {
> +		if (nla_len(port[IFLA_PORT_PROFILE]) != PORT_PROFILE_MAX) {
> +			memcpy(pp, &prev_pp, sizeof(*pp));
> +			return -EINVAL;
> +		}

If you have multiple error conditions with the same unwind, the common design
pattern in Linux is to use a goto error at end of function.