Re: [BUG] net: 3com: 3c59x: Possible null-pointer dereferences caused by Compaq PCI BIOS32 problem

[Tuo Li]

Hi Andrew,

On Fri, Dec 12, 2025 at 10:02 PM Andrew Lunn <andrew@xxxxxxx> wrote:
>
> On Fri, Dec 12, 2025 at 03:52:01PM +0800, Tuo Li wrote:
> > Hi,
> >
> > I found a few potential null-pointer dereferences in vortex_probe1() in
> > Linux 6.18.
>
> You might want to look at the history of this driver. The last time
> anybody seemed to really care about this driver was:
>
> commit a6522c08987daa6f9ac25a9c08870041a43db6b0
> Author: Neil Horman <nhorman@xxxxxxxxxxxxx>
> Date:   Thu Feb 25 13:02:50 2016 -0500
>
>     3c59x: mask LAST_FRAG bit from length field in ring
>
>     Recently, I fixed a bug in 3c59x:
>
>     commit 6e144419e4da11a9a4977c8d899d7247d94ca338
>     Author: Neil Horman <nhorman@xxxxxxxxxxxxx>
>     Date:   Wed Jan 13 12:43:54 2016 -0500
>
>         3c59x: fix another page map/single unmap imbalance
>
>     Which correctly rebalanced dma mapping and unmapping types.  Unfortunately it
>     introduced a new bug which causes oopses on older systems.
>
> Everything since then has been tree wide changes.
>
> > It looks like these issues stem from the call at line 987 used as a
> > workaround for the Compaq PCI BIOS32 problem:
>
> Also, maybe do some research into "Compaq PCI BIOS32". I _think_ that
> was from the time of the 80386? Maybe 80486? Support for those
> processors has been dropped, so i don't think it is even possible to
> boot such a machine to invoke this possible NULL pointer dereference.
>
> Please do some sanity checking before reporting potential issues. I
> _think_ you are wasting your own time, and valuable Maintainer time.
>
>         Andrew

Thanks for the explanation and for pointing me to the history of this
driver.

I apologize for the insufficient consideration. I'll be more careful about
checking the historical background and the practical reachability of code
paths before sending reports.

Thanks again for taking the time to clarify this.

Sincerely,
Tuo Li