===================================================================
@@ -436,18 +436,27 @@ static noinline int gup_hugepte(pte_t *p
return 1;
}
+static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
+ unsigned long sz)
+{
+ unsigned long __boundary = (addr + sz) & ~(sz-1);
+ return (__boundary - 1 < end - 1) ? __boundary : end;
+}
+
int gup_hugepd(hugepd_t *hugepd, unsigned pdshift,
unsigned long addr, unsigned long end,
int write, struct page **pages, int *nr)
{
pte_t *ptep;
unsigned long sz = 1UL << hugepd_shift(*hugepd);
+ unsigned long next;
ptep = hugepte_offset(hugepd, addr, pdshift);
do {
+ next = hugepte_addr_end(addr, end, sz);
if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
return 0;
- } while (ptep++, addr += sz, addr != end);
+ } while (ptep++, addr = next, addr != end);
return 1;
}
Commit a4fe3ce7699bfe1bd88f816b55d42d8fe1dac655 introduced a new get_user_pages() path for hugepages on powerpc. Unfortunately, there is a bug in it's loop logic, which can cause it to overrun the end of the intended region. This came about by copying the logic from the normal page path, which assumes the address and end parameters have been pagesize aligned at the top-level. Since they're not *hugepage* size aligned, the simplistic logic could step over the end of the gup region without triggering the loop end condition. This patch fixes the bug by using the technique that the normal page path uses in levels above the lowest to truncate the ending address to something we know we'll match with. Signed-off-by: David Gibson <david@gibson.dropbear.id.au>