[vbox-dev] Untested patch: suspected memory fault in falcon_clear_interrupts()

Adam Richter adamrichter4 at gmail.com
Mon Apr 29 21:13:28 UTC 2019

Hi, Michal.

I did not build that code.  I was just looking through the output of
cppcheck and did not want to ignore a complaint that appeared to be
real and not part of an upstream package.  Also, I think my previous
patch would generate a compiler warning about passing a const as a
non-const pointer, so I have attached an updated patch (which I also
hereby release under the terms of the MIT license).



On Mon, Apr 29, 2019 at 11:20 AM Michal Necasek
<michal.necasek at oracle.com> wrote:
>  Thanks for the patch. Just out of curiosity, did you check if the code is ever compiled in VirtualBox? I very much doubt we ever shipped that particular iPXE driver or ever intended to, and users would have to work quite hard to make the corresponding hardware appear in a VirtualBox VM.
>       Regards,
>           Michal
> ----- Original Message -----
> From: adamrichter4 at gmail.com
> To: vbox-dev at virtualbox.org
> Sent: Friday, April 26, 2019 9:46:10 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
> Subject: [vbox-dev] Untested patch: suspected memory fault in falcon_clear_interrupts()
> Hi.
> Running cppcheck on VirtualBox sources pointed me to what I think is a
> bug on falcon_clear_interrupts() will get a null pointer dereference
> is the PCI revision is not FALON_REV_B0.  I have attached a proposed
> patch and also appended that patch inline for easier reading.
> I am sorry that I have not even attempted to see if the patch compiles
> because I don't think I have time to do a VirtualBox build until at
> least the weekend.  As far as I know, I do not actually run code in
> this file.  Also, I have not been involved in contributing to
> VirtualBox development, so please excuse any violations of contributor
> conventions and please feel free to let me know how I can do better
> next time.
> If this patch compiles and there are no complaints, I request that you
> merge this patch or another fix for this issue more to your liking.  I
> hereby grant the permissions of the "MIT license" for any copyright
> interest I may have in this patch.  Please let me know if you need me
> to make any other statement so that you can merge this patch.
> Adam Richter
> Index: src/VBox/Devices/PC/ipxe/src/drivers/net/etherfabric.c
> ===================================================================
> --- src/VBox/Devices/PC/ipxe/src/drivers/net/etherfabric.c      (revision 78203)
> +++ src/VBox/Devices/PC/ipxe/src/drivers/net/etherfabric.c      (working copy)
> @@ -3798,7 +3798,8 @@
>         }
>         else {
>                 /* write to the INT_ACK register */
> -               falcon_writel ( efab, 0, FCN_INT_ACK_KER_REG_A1 );
> +               static const efab_dword_t zero;
> +               falcon_writel ( efab, &zero, FCN_INT_ACK_KER_REG_A1 );
>                 mb();
>                 falcon_readl ( efab, &reg,
>                                WORK_AROUND_BROKEN_PCI_READS_REG_KER_A1 );
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