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

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)