> -----Original Message-----
> From: Intel-wired-lan <[email protected]> On Behalf Of
> Simon Horman
> Sent: Thursday, November 27, 2025 3:45 AM
> To: Joshi, Sreedevi <[email protected]>
> Cc: [email protected]; [email protected]; Samudrala,
> Sridhar <[email protected]>; Tantilov, Emil S
> <[email protected]>; Loktionov, Aleksandr
> <[email protected]>; Paul Menzel <[email protected]>
> Subject: Re: [Intel-wired-lan] [PATCH iwl-net v2 1/3] idpf: Fix RSS LUT NULL
> pointer crash on early ethtool operations
>
> On Mon, Nov 24, 2025 at 12:47:48PM -0600, Sreedevi Joshi wrote:
> > The RSS LUT is not initialized until the interface comes up, causing
> > the following NULL pointer crash when ethtool operations like rxhash
> > on/off are performed before the interface is brought up for the first time.
> >
> > Move RSS LUT initialization from ndo_open to vport creation to ensure
> > LUT is always available. This enables RSS configuration via ethtool
> > before bringing the interface up. Simplify LUT management by
> > maintaining all changes in the driver's soft copy and programming
> > zeros to the indirection table when rxhash is disabled. Defer HW
> > programming until the interface comes up if it is down during rxhash and LUT
> configuration changes.
> >
> > Steps to reproduce:
> > ** Load idpf driver; interfaces will be created
> > modprobe idpf
> > ** Before bringing the interfaces up, turn rxhash off
> > ethtool -K eth2 rxhash off
> >
> > [89408.371875] BUG: kernel NULL pointer dereference, address:
> > 0000000000000000 [89408.371908] #PF: supervisor read access in kernel
> > mode [89408.371924] #PF: error_code(0x0000) - not-present page
> > [89408.371940] PGD 0 P4D 0 [89408.371953] Oops: Oops: 0000 [#1] SMP
> > NOPTI <snip> [89408.372052] RIP: 0010:memcpy_orig+0x16/0x130
> > [89408.372310] Call Trace:
> > [89408.372317] <TASK>
> > [89408.372326] ? idpf_set_features+0xfc/0x180 [idpf] [89408.372363]
> > __netdev_update_features+0x295/0xde0
> > [89408.372384] ethnl_set_features+0x15e/0x460 [89408.372406]
> > genl_family_rcv_msg_doit+0x11f/0x180
> > [89408.372429] genl_rcv_msg+0x1ad/0x2b0 [89408.372446] ?
> > __pfx_ethnl_set_features+0x10/0x10
> > [89408.372465] ? __pfx_genl_rcv_msg+0x10/0x10 [89408.372482]
> > netlink_rcv_skb+0x58/0x100 [89408.372502] genl_rcv+0x2c/0x50
> > [89408.372516] netlink_unicast+0x289/0x3e0 [89408.372533]
> > netlink_sendmsg+0x215/0x440 [89408.372551]
> __sys_sendto+0x234/0x240
> > [89408.372571] __x64_sys_sendto+0x28/0x30 [89408.372585]
> > x64_sys_call+0x1909/0x1da0 [89408.372604] do_syscall_64+0x7a/0xfa0
> > [89408.373140] ? clear_bhb_loop+0x60/0xb0 [89408.373647]
> > entry_SYSCALL_64_after_hwframe+0x76/0x7e
> > [89408.378887] </TASK>
> > <snip>
> >
> > Fixes: a251eee62133 ("idpf: add SRIOV support and other ndo_ops")
> > Signed-off-by: Sreedevi Joshi <[email protected]>
> > Reviewed-by: Sridhar Samudrala <[email protected]>
> > Reviewed-by: Emil Tantilov <[email protected]>
> > Reviewed-by: Aleksandr Loktionov <[email protected]>
> > Reviewed-by: Paul Menzel <[email protected]>
>
> Reviewed-by: Simon Horman <[email protected]>
Tested-by: Samuel Salin <[email protected]>
