netdev - Re: [PATCH] can: j1939: prevent allocation of j1939 filter for optlen = 0

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Date:   Mon, 21 Jun 2021 06:47:57 +0200
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     Norbert Slusarek <nslusarek@....net>
Cc:     netdev@...r.kernel.org, socketcan@...tkopp.net,
        linux-can@...r.kernel.org, mkl@...gutronix.de,
        kernel@...gutronix.de, kuba@...nel.org, davem@...emloft.net
Subject: Re: [PATCH] can: j1939: prevent allocation of j1939 filter for
 optlen = 0

Hi Norbert,

On Sun, Jun 20, 2021 at 02:38:42PM +0200, Norbert Slusarek wrote:
> If optval != NULL and optlen = 0 are specified for SO_J1939_FILTER in
> j1939_sk_setsockopt(), memdup_sockptr() will return ZERO_PTR for 0 size
> allocation. The new filter will be mistakenly assigned ZERO_PTR.
> This patch checks for optlen != 0 and filter will be assigned NULL
> in case of optlen = 0.
> 
> Fixes: a7b75c5a8c41 ("net: pass a sockptr_t into ->setsockopt")
> Signed-off-by: Norbert Slusarek <nslusarek@....net>

Acked-by: Oleksij Rempel <o.rempel@...gutronix.de>

Thank you!

> ---
>  net/can/j1939/socket.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/can/j1939/socket.c b/net/can/j1939/socket.c
> index 56aa66147d5a..ff20cb629200 100644
> --- a/net/can/j1939/socket.c
> +++ b/net/can/j1939/socket.c
> @@ -673,7 +673,7 @@ static int j1939_sk_setsockopt(struct socket *sock, int level, int optname,
> 
>  	switch (optname) {
>  	case SO_J1939_FILTER:
> -		if (!sockptr_is_null(optval)) {
> +		if (!sockptr_is_null(optval) && optlen != 0) {
>  			struct j1939_filter *f;
>  			int c;
> 
> --
> 2.30.2
> 
> 

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