From: Oliver Hartkopp <socketcan@hartkopp.net>
To: Richard Palethorpe <rpalethorpe@suse.com>, linux-can@vger.kernel.org
Cc: Kees Cook <keescook@chromium.org>,
netdev@vger.kernel.org, security@kernel.org, wg@grandegger.com,
mkl@pengutronix.de, davem@davemloft.net
Subject: Re: [PATCH v2] slcan: Don't transmit uninitialized stack data in padding
Date: Wed, 1 Apr 2020 21:41:09 +0200 [thread overview]
Message-ID: <4ec16ff5-7126-ffa2-491f-520606a038a9@hartkopp.net> (raw)
In-Reply-To: <20200401100639.20199-1-rpalethorpe@suse.com>
On 01/04/2020 12.06, Richard Palethorpe wrote:
> struct can_frame contains some padding which is not explicitly zeroed in
> slc_bump. This uninitialized data will then be transmitted if the stack
> initialization hardening feature is not enabled (CONFIG_INIT_STACK_ALL).
>
> This commit just zeroes the whole struct including the padding.
>
> Signed-off-by: Richard Palethorpe <rpalethorpe@suse.com>
> Fixes: a1044e36e457 ("can: add slcan driver for serial/USB-serial CAN adapters")
> Reviewed-by: Kees Cook <keescook@chromium.org>
> Cc: linux-can@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Cc: security@kernel.org
> Cc: wg@grandegger.com
> Cc: mkl@pengutronix.de
> Cc: davem@davemloft.net
Acked-by: Oliver Hartkopp <socketcan@hartkopp.net>
> ---
>
> V2: Reviewed by Kees and Fixes tag added.
>
> As mentioned in V1; The following unfinished test can reproduce the bug:
> https://github.com/richiejp/ltp/blob/pty-slcan/testcases/kernel/pty/pty04.c
>
>
> drivers/net/can/slcan.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
> index a3664281a33f..4dfa459ef5c7 100644
> --- a/drivers/net/can/slcan.c
> +++ b/drivers/net/can/slcan.c
> @@ -148,7 +148,7 @@ static void slc_bump(struct slcan *sl)
> u32 tmpid;
> char *cmd = sl->rbuff;
>
> - cf.can_id = 0;
> + memset(&cf, 0, sizeof(cf));
>
> switch (*cmd) {
> case 'r':
> @@ -187,8 +187,6 @@ static void slc_bump(struct slcan *sl)
> else
> return;
>
> - *(u64 *) (&cf.data) = 0; /* clear payload */
> -
> /* RTR frames may have a dlc > 0 but they never have any data bytes */
> if (!(cf.can_id & CAN_RTR_FLAG)) {
> for (i = 0; i < cf.can_dlc; i++) {
>
prev parent reply other threads:[~2020-04-01 19:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-01 10:06 [PATCH v2] slcan: Don't transmit uninitialized stack data in padding Richard Palethorpe
2020-04-01 10:08 ` Marc Kleine-Budde
2020-04-01 18:23 ` David Miller
2020-04-01 19:41 ` Oliver Hartkopp [this message]
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