slcan: Don't transmit uninitialized stack data in padding

[ Upstream commit b9258a2cece4ec1f020715fe3554bc2e360f6264 ]

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: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/can/slcan.c b/drivers/net/can/slcan.c
index 94b37c6..d0435c7 100644 (file)
--- a/drivers/net/can/slcan.c
+++ b/drivers/net/can/slcan.c
@@ -147,7 +147,7 @@ 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':
@@ -186,8 +186,6 @@ 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++) {