Re: [PATCH net] net: bcmgenet: fix NULL dereference in set_coalesce before first open

[Florian Fainelli]

On 9/28/26 03:56, Nicolai Buchwitz wrote:
> The Rx ring priv and index are only set in bcmgenet_init_rx_ring(),
> which runs at open. Setting the Rx coalescing parameters on an interface
> that was never opened, e.g. "ethtool -C eth0 rx-usecs 50", dereferences
> a NULL ring->priv. The oops happens with RTNL held, so networking
> stays stuck until a reboot:
>
>    Unable to handle kernel paging request at virtual address 0000000000002788
>    pc : bcmgenet_set_rx_coalesce.isra.0+0x10/0x88
>    lr : bcmgenet_set_coalesce+0xe8/0x180
>    Call trace:
>     bcmgenet_set_rx_coalesce.isra.0+0x10/0x88 (P)
>     __ethnl_set_coalesce.isra.0+0x490/0x570
>     ethnl_set_coalesce+0x48/0xc0
>     ethnl_default_set_doit+0xf4/0x230
>     genl_family_rcv_msg_doit+0xe8/0x160
>     genl_rcv_msg+0x220/0x2a0
>     netlink_rcv_skb+0x68/0x140
>     genl_rcv+0x40/0x60
>     netlink_unicast+0x338/0x3c0
>     netlink_sendmsg+0x19c/0x3f8
>     __sock_sendmsg+0x64/0xc0
>     __sys_sendto+0x124/0x198
>     __arm64_sys_sendto+0x30/0x48
>
> Set priv and index at probe. Writing the registers while the interface
> is down is harmless because open resets the MAC and
> bcmgenet_init_rx_coalesce() reapplies the stored values.
>
> Fixes: 9f4ca05827a2 ("net: bcmgenet: Add support for adaptive RX coalescing")
> Signed-off-by: Nicolai Buchwitz <nb@xxxxxxxxxxx>

Reviewed-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>

Thanks Nicolai!
--
Florian