3.16.45-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Helge Deller <[email protected]> commit bd726c90b6b8ce87602208701b208a208e6d5600 upstream. 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 <[email protected]> Acked-by: Hugh Dickins <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> --- mm/mmap.c | 13 ++++++++----- 1 file changed, 8 insertions(+), 5 deletions(-) --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2139,16 +2139,19 @@ int expand_upwards(struct vm_area_struct if (!(vma->vm_flags & VM_GROWSUP)) return -EFAULT; - /* Guard against wrapping around to address 0. */ + /* Guard against exceeding limits of the address space. */ address &= PAGE_MASK; - address += PAGE_SIZE; - if (!address) + if (address >= TASK_SIZE) return -ENOMEM; + address += PAGE_SIZE; /* Enforce 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; if (next && next->vm_start < gap_addr) { if (!(next->vm_flags & VM_GROWSUP))
