Re: [Intel-wired-lan] ixgbe: NULL-pointer panic in ixgbe_check_mdd_event() when SR-IOV disabled (num_vfs=0)

Re: [Intel-wired-lan] ixgbe: NULL-pointer panic in ixgbe_check_mdd_event() when SR-IOV disabled (num_vfs=0)

[Przemek Kitszel]

On 8/3/26 16:47, Viacheslav Tyryshkin wrote:
> Hello
> I'm hitting the bug daily with Intel X550.
> please be informed, i may provide kernel dumps on request.
> 
> ## One-line
> On an Intel X550 with **no VFs configured** (`sriov_numvfs=0`), a
> spurious MDD interrupt reaches `ixgbe_check_mdd_event()`, which writes
> into `adapter->vfinfo[]` without guarding for `num_vfs==0` — and
> `vfinfo` is NULL when SR-IOV is off → kernel panic in interrupt context.
> Reproduces roughly once a day under normal operation.

by looking at the code this is weird

ixgbe_handle_mdd_x550() reads two registers into wqbr, and the combined
read must be not-zero to trigger what you are observing

A patch will be much welcomed, given all the work you did with hunting
it down.
(avoid html, target at current iwl-net tree)