On Mon, Dec 19, 2011 at 6:18 PM, Ben Hutchings ben@decadent.org.uk wrote:
On Mon, 2011-12-19 at 16:14 -0800, Kees Cook wrote:
On Mon, Dec 19, 2011 at 4:09 PM, Ben Hutchings ben@decadent.org.uk wrote:
Kees, in commit 01e2f533a234dc62d16c0d3d4fb9d71cf1ce50c3 ("drm: do not leak kernel addresses via /proc/dri/*/vma") you changed the logging of high_memory:
- seq_printf(m, "vma use count: %d, high_memory = %p, 0x%08llx\n",
- seq_printf(m, "vma use count: %d, high_memory = %pK, 0x%pK\n",
atomic_read(&dev->vma_count),
- high_memory, (u64)virt_to_phys(high_memory));
- high_memory, (void *)virt_to_phys(high_memory));
This doesn't make sense because the physical address may be truncated (in theory at least).
Leaking even a truncated address is still a problem, IMO. Or do you mean there is some side-effect causing a problem?
I mean that this the conversion to void * can be a narrowing conversion, so when printing of kernel pointers is enabled the full physical address may not be displayed.
Ah-ha, okay, I see what you mean now. This is, as you say, only a problem "in theory". Is it worth fixing currently? If so, we probably need to add the "K" option to %x in some fashion.
-Kees