Il 29/10/2013 9.44, Paolo Minazzi ha scritto:
Hi to all,
I think the function "generic_access_phys" in mm/memory.c has got a
small bug.
THe ioremap_prot is called with the parameter size=PAGE_SIZE.
But it can happen that we need more than one page, and this will
produce a kernel fault.
int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
void *buf, int len, int write)
{
resource_size_t phys_addr;
unsigned long prot = 0;
void __iomem *maddr;
int offset = addr & (PAGE_SIZE-1);
if (follow_phys(vma, addr, write, &prot, &phys_addr))
return -EINVAL;
====> maddr = ioremap_prot(phys_addr, PAGE_SIZE);
if (write)
memcpy_toio(maddr + offset, buf, len);
else
memcpy_fromio(buf, maddr + offset, len);
iounmap(maddr);
return len;
}
I think that the ioremap_prot should be changed with
maddr = ioremap_prot(phys_addr, ((phys_addr + offset + len - 1) &
~(PAGE_SIZE-1)) -
phys_addr + PAGE_SIZE);
Thanks,
Paolo Minazzi
This is a more simple patch in the usual diff format:
diff -r 6321bc9c43db linux-2.6.31.8/mm/memory.c
--- a/linux-2.6.31.8/mm/memory.c Tue Oct 22 13:35:14 2013 +0200
+++ b/linux-2.6.31.8/mm/memory.c Tue Oct 29 11:44:51 2013 +0100
@@ -3264,1 +3264,1 @@
- maddr = ioremap_prot(phys_addr, PAGE_SIZE);
+ maddr = ioremap_prot(phys_addr, ((offset + len - 1) &
~(PAGE_SIZE-1)) + PAGE_SIZE );
Regards,
Paolo Minazzi
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