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Allow stack to grow up to address space limit

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Fix expand_upwards() on architectures with an upward-growing stack (parisc,
metag and partly IA-64) to allow the stack to reliably grow exactly up to
the address space limit given by TASK_SIZE.

Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Helge Deller 2017-06-19 17:34:05 +02:00 • committed by Linus Torvalds
parent f4cb767d76
commit bd726c90b6
1 changed files with 8 additions and 5 deletions
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13
mm/mmap.c
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@ -2230,16 +2230,19 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address)
if (!(vma->vm_flags & VM_GROWSUP)) if (!(vma->vm_flags & VM_GROWSUP))
return -EFAULT; return -EFAULT;
/* Guard against wrapping around to address 0. */ /* Guard against exceeding limits of the address space. */
address &= PAGE_MASK; address &= PAGE_MASK;
address += PAGE_SIZE; if (address >= TASK_SIZE)
if (!address)
return -ENOMEM; return -ENOMEM;
address += PAGE_SIZE;
/* Enforce stack_guard_gap */ /* Enforce stack_guard_gap */
gap_addr = address + stack_guard_gap; gap_addr = address + stack_guard_gap;
if (gap_addr < address)
return -ENOMEM; /* Guard against overflow */
if (gap_addr < address || gap_addr > TASK_SIZE)
gap_addr = TASK_SIZE;
next = vma->vm_next; next = vma->vm_next;
if (next && next->vm_start < gap_addr) { if (next && next->vm_start < gap_addr) {
if (!(next->vm_flags & VM_GROWSUP)) if (!(next->vm_flags & VM_GROWSUP))