Re: [PATCH 3/5] PCI/ERR: get device before call device driver to avoid null pointer reference

Andy Shevchenko
2020-09-29T08:51:15Z

On Tue, Sep 29, 2020 at 10:35:14AM +0800, Ethan Zhao wrote:
> Preferred style, there will be cleared comment in v6.

Avoid top postings.

> On Sat, Sep 26, 2020 at 12:42 AM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:
> >
> > On Thu, Sep 24, 2020 at 10:34:21PM -0400, Ethan Zhao wrote:
> > > During DPC error injection test we found there is race condition between
> > > pciehp and DPC driver, null pointer reference caused panic as following
> >
> > null -> NULL
> >
> > >
> > > # setpci -s 64:02.0 0x196.w=000a
> > > // 64:02.0 is rootport has DPC capability
> > > # setpci -s 65:00.0 0x04.w=0544
> > > // 65:00.0 is NVMe SSD populated in above port
> > > # mount /dev/nvme0n1p1 nvme
> > >
> > > (tested on stable 5.8 & ICX platform)
> > >
> > > Buffer I/O error on dev nvme0n1p1, logical block 468843328,
> > > async page read
> > > BUG: kernel NULL pointer dereference, address: 0000000000000050
> > > #PF: supervisor read access in kernel mode
> > > #PF: error_code(0x0000) - not-present page
> >
> > Same comment about Oops.

In another thread it was a good advice to move the full Oops (if you think it's
very useful to have) after the cutter '---' line, so it will be in email
archives but Git history.