Re: potential overflow in de4x5.c

On Thu, Jan 07, 2010 at 06:40:07PM +0300, Dan Carpenter wrote:

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#define MOTO_SROM_BUG    (lp->active == 8 && (get_unaligned_le32(dev->dev_addr) & 0x00ffffff) == 0x3e0008)

...

Basically the MOTO_SROM_BUG macro is asking:  Do we have an array overflow 
and a hardware bug?  If so we had better do something about the hardware
bug.  It sounds silly to me.

Hardware bug? A firmware bug I think.

I read the MOTO_SROM_BUG to be using both "active" and "dev_addr"
to be certain it was dealing with a broken SROM. And then fixing up
the "bork3d" values reported by the SROM (setting active to 0).

This still leaves open the question about when lp->active
could be >= DE4X5_MAX_MII. 

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BTW, someone suggested to fix up this same bit of code before:
   http://www.mail-archive.com/netdev@vger.kernel.org/msg09838.html

And I'm not sure why that patch wasn't accepted then either. Patch looks fine to me.

Someone has updated the code since he posted the patch, presumably to fix
the second overflow he mentioned.

*nod*

There is still another one left unfixed though which smatch misses.  

  5073          if ((j == limit) && (i < DE4X5_MAX_MII)) {
  5074              for (k=0; k < DE4X5_MAX_PHY && lp->phy[k].id; k++);
  5075              lp->phy[k].addr = i;

k could be == DE4X5_MAX_PHY on line 5075.

Yup. In theory at least. But can anyone point me at a DE4X5 device that
could have 7 or more phys attached to it?
I expect no more than three cases (thin_lan Coax, RJ45, MAU) but am
probably missing a few others - unlikely more than one or two more.

One unlikely but possible case: broken HW which reads ~0U (PCI Master Abort)
for phy[] values.

cheers,
grant