UBUNTU: Ubuntu-raspi2-4.10.0-1000.1

[mirror_ubuntu-zesty-kernel.git] / mm / mmap.c

diff --git a/mm/mmap.c b/mm/mmap.c
index ef78a5ca5599bee6e62607e4e00a81705f0da388..09c728a1eeee248b3af92f401db9c3b037f64570 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -2240,7 +2240,8 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
                gap_addr = TASK_SIZE;
 
        next = vma->vm_next;
-       if (next && next->vm_start < gap_addr) {
+       if (next && next->vm_start < gap_addr &&
+                       (next->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
                if (!(next->vm_flags & VM_GROWSUP))
                        return -ENOMEM;
                /* Check that both stack segments have the same anon_vma? */
@@ -2311,7 +2312,6 @@ int expand_downwards(struct vm_area_struct *vma,
 {
        struct mm_struct *mm = vma->vm_mm;
        struct vm_area_struct *prev;
-       unsigned long gap_addr;
        int error;
 
        address &= PAGE_MASK;
@@ -2320,14 +2320,12 @@ int expand_downwards(struct vm_area_struct *vma,
                return error;
 
        /* Enforce stack_guard_gap */
-       gap_addr = address - stack_guard_gap;
-       if (gap_addr > address)
-               return -ENOMEM;
        prev = vma->vm_prev;
-       if (prev && prev->vm_end > gap_addr) {
-               if (!(prev->vm_flags & VM_GROWSDOWN))
+       /* Check that both stack segments have the same anon_vma? */
+       if (prev && !(prev->vm_flags & VM_GROWSDOWN) &&
+                       (prev->vm_flags & (VM_WRITE|VM_READ|VM_EXEC))) {
+               if (address - prev->vm_end < stack_guard_gap)
                        return -ENOMEM;
-               /* Check that both stack segments have the same anon_vma? */
        }
 
        /* We must make sure the anon_vma is allocated. */