From aa4d9603069503207e399b6240d12b46a8df6414 Mon Sep 17 00:00:00 2001 From: Corinna Vinschen Date: Tue, 7 Apr 2020 14:09:45 +0200 Subject: [PATCH] Cygwin: threads: use mmap area to fulfill requests for big stacks Otherwise big stacks have a higher probability to collide with randomized PEBs and TEBs after fork. Signed-off-by: Corinna Vinschen --- winsup/cygwin/miscfuncs.cc | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/winsup/cygwin/miscfuncs.cc b/winsup/cygwin/miscfuncs.cc index 1ed9684f1..e1eb5e8e2 100644 --- a/winsup/cygwin/miscfuncs.cc +++ b/winsup/cygwin/miscfuncs.cc @@ -515,11 +515,13 @@ public: BOOL overflow = FALSE; PVOID real_stackaddr = NULL; - /* If an application requests a monster stack, we fulfill this request - from outside of our pool, top down. */ + /* If an application requests a monster stack, fulfill request + from mmap area. */ if (real_size > THREAD_STACK_MAX) - return VirtualAlloc (NULL, real_size, MEM_RESERVE | MEM_TOP_DOWN, - PAGE_READWRITE); + { + PVOID addr = mmap_alloc.alloc (NULL, real_size, false); + return VirtualAlloc (addr, real_size, MEM_RESERVE, PAGE_READWRITE); + } /* Simple round-robin. Keep looping until VirtualAlloc succeeded, or until we overflowed and hit the current address. */ for (UINT_PTR addr = current - real_size;