From mboxrd@z Thu Jan 1 00:00:00 1970 From: Helge Deller Subject: [PATCH v2] mm: Fix overflow check in expand_upwards() Date: Sun, 2 Jul 2017 21:24:52 +0200 Message-ID: <20170702192452.GA11868@p100.box> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Cc: =?iso-8859-15?Q?J=F6rn?= Engel , linux-parisc@vger.kernel.org To: Hugh Dickins , linux-kernel@vger.kernel.org Return-path: List-ID: List-Id: linux-parisc.vger.kernel.org Jörn Engel noticed that the expand_upwards() function might not return -ENOMEM in case the requested address is (unsigned long)-PAGE_SIZE and if the architecture didn't defined TASK_SIZE as multiple of PAGE_SIZE. Affected architectures are arm, frv, m68k, blackfin, h8300 and xtensa which all define TASK_SIZE as 0xffffffff, but since none of those have an upwards-growing stack we currently have no actual issue. Nevertheless let's fix this just in case any of the architectures with an upward-growing stack (currently parisc, metag and partly ia64) define TASK_SIZE similar. Reported-by: Jörn Engel Fixes: bd726c90b6b8 ("Allow stack to grow up to address space limit") Cc: stable@vger.kernel.org Signed-off-by: Helge Deller diff --git a/mm/mmap.c b/mm/mmap.c index a5e3dcd..cc2fc8a 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -2232,7 +2232,7 @@ int expand_upwards(struct vm_area_struct *vma, unsigned long address) /* Guard against exceeding limits of the address space. */ address &= PAGE_MASK; - if (address >= TASK_SIZE) + if (address >= (TASK_SIZE & PAGE_MASK)) return -ENOMEM; address += PAGE_SIZE;