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Subject[PATCH 4/19] fix checks for expand-in-place mremap
From

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
mm/mremap.c | 13 +++++++++++--
1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/mm/mremap.c b/mm/mremap.c
index 90e422c..9d07539 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -27,6 +27,10 @@

#include "internal.h"

+#ifndef arch_mmap_check
+#define arch_mmap_check(addr, len, flags) (0)
+#endif
+
static pmd_t *get_old_pmd(struct mm_struct *mm, unsigned long addr)
{
pgd_t *pgd;
@@ -368,12 +372,17 @@ out:

static int vma_expandable(struct vm_area_struct *vma, unsigned long delta)
{
+ unsigned long end = vma->vm_end + delta;
unsigned long max_addr = TASK_SIZE;
if (vma->vm_next)
max_addr = vma->vm_next->vm_start;
- if (max_addr - vma->vm_end < delta)
+ if (max_addr < end || end < vma->vm_end)
+ return 0;
+ if (arch_mmap_check(vma->vm_start, end - vma->vm_start, MAP_FIXED))
+ return 0;
+ if (get_unmapped_area(NULL, vma->vm_start, end - vma->vm_start,
+ 0, MAP_FIXED) & ~PAGE_MASK)
return 0;
- /* we need to do arch-specific checks here */
return 1;
}

--
1.5.6.5



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