Hi Marc,
On 11.05.22 16:57, Oliver Hartkopp wrote:
On 5/11/22 16:54, Marc Kleine-Budde wrote:
On 11.05.2022 16:50:06, Oliver Hartkopp wrote:
On 5/11/22 16:36, Marc Kleine-Budde wrote:
On 11.05.2022 15:24:21, Marc Kleine-Budde wrote:
On 11.05.2022 14:38:32, Oliver Hartkopp wrote:
IMO this patch does not work as intended.
You probably need to revisit every place where can_skb_reserve()
is used,
e.g. in raw_sendmsg().
And the loopback for devices that don't support IFF_ECHO:
| https://elixir.bootlin.com/linux/latest/source/net/can/af_can.c#L257
BTW: There is a bug with interfaces that don't support IFF_ECHO.
Assume an invalid CAN frame is passed to can_send() on an interface
that
doesn't support IFF_ECHO. The above mentioned code does happily
generate
an echo frame and it's send, even if the driver drops it, due to
can_dropped_invalid_skb(dev, skb).
The echoed back CAN frame is treated in raw_rcv() as if the headroom
is valid:
I double checked that code and when I didn't miss anything all the
callers of can_send() (e.g. raw_sendmsg()) are creating valid skbs.
https://elixir.bootlin.com/linux/v5.17.6/A/ident/can_send
| https://elixir.bootlin.com/linux/v5.17.6/source/net/can/raw.c#L138
But as far as I can see the can_skb_headroom_valid() check never has
been done. What about this patch?
index 1fb49d51b25d..fda4807ad165 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -255,6 +255,9 @@ int can_send(struct sk_buff *skb, int loop)
*/
if (!(skb->dev->flags & IFF_ECHO)) {
+ if (can_dropped_invalid_skb(dev, skb))
+ return -EINVAL;
+
That would make this change unnecessary, right?
IIRC the reason for can_dropped_invalid_skb() is to prove valid skbs for
CAN interface drivers when CAN frame skbs are created e.g. with
PF_PACKET sockets.
Best,
Oliver
Good point!
But please check the rest of the code.
You need 'goto inval_skb;' instead of the return ;-)
Why? To free the skb? That's what can_dropped_invalid_skb() does, too:
|
https://elixir.bootlin.com/linux/v5.17.6/source/include/linux/can/skb.h#L130
My bad!
Pointing you not reading the code ... should better have looked myself :-D
