Andrew, Paulus, please apply
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 <[EMAIL PROTECTED]>
Index: working-2.6/arch/powerpc/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/powerpc/mm/hugetlbpage.c 2006-12-21
14:54:15.000000000 +1100
+++ working-2.6/arch/powerpc/mm/hugetlbpage.c 2006-12-21 14:57:35.000000000
+1100
@@ -744,7 +744,8 @@ static int htlb_check_hinted_area(unsign
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 @@ unsigned long hugetlb_get_unmapped_area(
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 @@ unsigned long hugetlb_get_unmapped_area(
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 */
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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