[POWERPC] Fix bogus BUG_ON() in in hugetlb_get_unmapped_area()
The powerpc specific version of hugetlb_get_unmapped_area() makes some
unwarranted assumptions about what checks have been made to its
parameters by its callers. This will lead to a BUG_ON() if a 32-bit
process attempts to make a hugepage mapping which extends above
TASK_SIZE (4GB).
I'm not sure if these assumptions came about because they were valid
with earlier versions of the get_unmapped_area() path, or if it was
always broken. Nonetheless this patch fixes the logic, and removes
the crash.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index 89c836d..1bb20d8 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -744,7 +744,8 @@
struct vm_area_struct *vma;
vma = find_vma(current->mm, addr);
- if (!vma || ((addr + len) <= vma->vm_start))
+ if (TASK_SIZE - len >= addr &&
+ (!vma || ((addr + len) <= vma->vm_start)))
return 0;
return -ENOMEM;
@@ -815,6 +816,8 @@
return -EINVAL;
if (len & ~HPAGE_MASK)
return -EINVAL;
+ if (len > TASK_SIZE)
+ return -ENOMEM;
if (!cpu_has_feature(CPU_FTR_16M_PAGE))
return -EINVAL;
@@ -823,9 +826,6 @@
BUG_ON((addr + len) < addr);
if (test_thread_flag(TIF_32BIT)) {
- /* Paranoia, caller should have dealt with this */
- BUG_ON((addr + len) > 0x100000000UL);
-
curareas = current->mm->context.low_htlb_areas;
/* First see if we can use the hint address */